Version History
The current version is 3.3-0

These articles highlight the key improvements in major and minor version releases (for example, 2.2) and explain their significance. To view a complete list of changes per release (including minor changes and bug fixes), please see the release notes (next tab).
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Another season, another GATK release. Personally, Fall is my favorite season, and while I don’t want to play favorites with versions (though unlike with children, you’re allowed to say that the most recent one is the best --and you can tell I was a youngest child) this one is pretty special to me.

Because -ploidy! Yeah, that’s really all I need to say about that. I was a microbiologist once. And I expect many plant people will be happy too.

Other cool stuff detailed below includes: full functionality for the genotype refinement workflow tools; physical phasing and appropriate handling of dangly bits by HaplotypeCaller (must… resist… jokes…); a wealth of new documentation for variant annotations; and a slew of bug fixes that I won’t go over but are listed in the release notes.

Genotype refinement workflow with all the trimmings

As announced earlier this week, we recently developed a workflow for refining genotype calls, intended for researchers who need highly accurate genotype information as well as preliminary identification of possible de novo mutations (see the documentation for details). Although all the tools involved were already available in GATK 3.2, some functionalities were not, so we’re very happy to finally make all of them available in this new version. Plus, we like the new StrandOddsRatio annotation (which sort of replaces FisherStrand for estimating strand bias) so much that we made it a standard one, and it now gets annotated by default.

Non-diploids, rejoice!

This is also a feature that was announced a little while ago, but until now was only fully available in the nightly builds, which are technically unsupported unless we tell you to use them to get past a bad bug. In this new release, both HaplotypeCaller and GenotypeGVCFs are able to deal with non-diploid organisms (whether haploid or exotically polyploid). In the case of HaplotypeCaller, you need to specify the ploidy of your non-diploid sample with the -ploidy argument. HC can only deal with one ploidy at a time, so if you want to process different chromosomes with different ploidies (e.g. to call X and Y in males) you need to run them separately. On the bright side, you can combine the resulting files afterward. In particular, if you’re running the -ERC GVCF workflow, you’ll find that both CombineGVCFs and GenotypeGVCFs are able to handle mixed ploidies (between locations and between samples). Both tools are able to correctly work out the ploidy of any given sample at a given site based on the composition of the GT field, so they don’t require you to specify the -ploidy argument.

HaplotypeCaller gets physical

You know how HC performs a complete reassembly of reads in an ActiveRegion? (If you don’t, go read this now. Go on, we’ll wait for you.) Well, this involves building an assembly graph, of course (of course!), and it produces a list of haplotypes. Fast-forward a couple of steps, and you end up with a list of variants. That’s great, but until now, those variants were unphased, meaning the HC didn’t give you any information about whether any two variants’ alleles were on the same haplotype (meaning, on the same physical piece of DNA) or not. For example, you’d want to know whether you had this:

or this:

But HC wouldn’t tell you which it was in its output. Which was a shame, because the HC sees that information! It took a little tweaking to get it to talk, but now it emits physical phasing by default in its GVCF output (both banded GVCF and BP_RESOLUTION).

In a nutshell, phased records will look like this:

1   1372243  .  T  <NON_REF>  .  .  END=1372267  <snip>  <snip>
1   1372268  .  G  A,<NON_REF>  .  .  <snip>  GT:AD:DP:GQ:PGT:PID:PL:SB 0/1:30,40,0:70:99:0|1:1372268_G_A:<snip>
1   1372269  .  G  T,<NON_REF>  .  .  <snip>  GT:AD:DP:GQ:PGT:PID:PL:SB 0/1:30,41,0:71:99:0|1:1372268_G_A:<snip>
1   1372270  .  C  <NON_REF>  .  .  END=1372299  <snip>  <snip>

You see that the phasing info is encoded in two new sample-level annotations, PID (for phase identifier) and PGT (phased genotype). More than two variants can be phased in a group with the same PID, and that can include mixed types of variants (e.g. SNPs and indels).

The one big caveat related to the physical phasing output by HC in GVCFs is that, like the GVCF itself, it is not intended to be used directly for analysis! You must run your GVCFs through GenotypeGVCFs in order to get the finalized, properly formatted, ready-for-analysis calls.

Heads or tails

Speaking of HaplotypeCaller getting more helpful all the time, here’s some more of that. This still has to do with the graph assembly, and specifically, with how HC handles the bits at the edges of the graph, which are called dangling heads and dangling tails. Without going too far into the details, let’s just say that sometimes you have a variant that’s near the edge of a covered region, and due to technical reasons (cough kmer size cough) the end of the variant path can’t be tied back into the reference path, so it just dangles there (like, say, Florida) and gets trimmed off in the next step (rising ocean levels). And thus the variant is lost (boo).

We originally started paying attention to this because it often happens at the edge of exons near splice junctions in RNAseq data, but it can also happen in DNA data. The solution was to give HC the ability to recover these cliff-dwelling variants by merging the dangling ends back into the graph using special logic tailored for those situations. If you have been using our RNAseq Best Practices, then you may recognize this as the logic invoked by the --recoverDanglingHeads argument. In the new version, the functionality has been improved further and is now enabled by default for all variant calling (so you no longer need to specify that argument for RNAseq analysis). The upshot is that sensitivity is improved, especially for RNAseq data but also for DNA.

Variant annotations finally make sense

Finally, I want to attract everyone’s attention to the Variant Annotations section of the Tool Documentation, which has just undergone a comprehensive overhaul. All annotations now have some kind of documentation outlining their general purpose, output, interpretation, caveats and some notes about how they’re calculated where applicable. Tell us what you think; we are feedback junkies.

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Better late than never (right?), here are the version highlights for GATK 3.2. Overall, this release is essentially a collection of bug fixes and incremental improvements that we wanted to push out to not keep folks waiting while we're working on the next big features. Most of the bug fixes are related to the HaplotypeCaller and its "reference confidence model" mode (which you may know as -ERC GVCF). But there are also a few noteworthy improvements/changes in other tools which I'll go over below.

Working out the kinks in the "reference confidence model" workflow

The "reference confidence model" workflow, which I hope you have heard of by now, is that awesome new workflow we released in March 2014, which was the core feature of the GATK 3.0 version. It solves the N+1 problem and allows you to perform joint variant analysis on ridiculously large cohorts without having to enslave the entire human race and turning people into batteries to power a planet-sized computing cluster. More on that later (omg we're writing a paper on it, finally!).

You can read the full list of improvements we've made to the tools involved in the workflow (mainly HaplotypeCaller and Genotype GVCFs) in Eric's (unusually detailed) Release Notes for this version. The ones you are most likely to care about are that the "missing PLs" bug is fixed, GenotypeGVCFs now accepts arguments that allow it to emulate the HC's genotyping capabilities more closely (such as --includeNonVariantSites), the AB annotation is fully functional, reference DPs are no longer dropped, and CatVariants now accepts lists of VCFs as input. OK, so that last one is not really specific to the reference model pipeline, but that's where it really comes in handy (imagine generating a command line with thousands of VCF filenames -- it's not pretty).

HaplotypeCaller now emits post-realignment coverage metrics

The coverage metrics (DP and AD) reported by HaplotypeCaller are now those calculated after the HC's reassembly step, based on the reads having been realigned to the most likely haplotypes. So the metrics you see in the variant record should match what you see if you use the -bamout option and visualize the reassembled ActiveRegion in a genome browser such as IGV. Note that if any of this is not making sense to you, say so in the comments and we'll point you to the new HaplotypeCaller documentation! Or, you know, look for it in the Guide.

R you up to date on your libraries?

We updated the plotting scripts used by BQSR and VQSR to use the latest version of ggplot2, to get rid of some deprecated function issues. If your Rscripts are suddenly failing, you'll need to update your R libraries.

A sincere apology to GATK-based tool developers

We're sorry for making you jump through all these hoops recently. As if the switch to Maven wasn't enough, we have now completed a massive reorganization/renaming of the codebase that will probably cause you some headaches when you port your tools to the newest version. But we promise this is the last big wave, and ultimately this will make your life easier once we get the GATK core framework to be a proper maven artifact.

In a nutshell, the base name of the codebase has changed from sting to gatk (which hopefully makes more sense), and the most common effect is that sting.gatk classpath segments are now This, by the way, is why we had a bunch of broken documentation links; most of these have been fixed (yay symlinks) but there may be a few broken URLs remaining. If you see something, say something, and we'll fix it.

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This may seem crazy considering we released the big 3.0 version not two weeks ago, but yes, we have a new version for you already! It's a bit of a special case because this release is all about the hardware-based optimizations we had previously announced. What we hadn't announced yet was that this is the fruit of a new collaboration with a team at Intel (which you can read more about here), so we were waiting for everyone to be ready for the big reveal.

Intel inside GATK

So basically, the story is that we've started collaborating with the Intel Bio Team to enable key parts of the GATK to run more efficiently on certain hardware configurations. For our first project together, we tackled the PairHMM algorithm, which is responsible for a large proportion of the runtime of HaplotypeCaller analyses. The resulting optimizations, which are the main feature in version 3.1, produce significant speedups for HaplotypeCaller runs on a wide range of hardware.

We will continue working with Intel to further improve the performance of GATK tools that have historically been afflicted with performance issues and long runtimes (hello BQSR). As always, we hope these new features will make your life easier, and we welcome your feedback in the forum!

In practice

Note that these optimizations currently work on Linux systems only, and will not work on Mac or Windows operating systems. In the near future we will add support for Mac OS. We have no plans to add support for Windows since the GATK itself does not run on Windows.

Please note also that to take advantage of these optimizations, you need to opt-in by adding the following flag to your GATK command: -pairHMM VECTOR_LOGLESS_CACHING.

Here is a handy little table of the speedups you can expect depending on the hardware and operating system you are using. The configurations given here are the minimum requirements for benefiting from the expected speedup ranges shown in the third column. Keep in mind that these numbers are based on tests in controlled conditions; in the wild, your mileage may vary.

Linux kernel version Architecture / Processor Expected speedup Instruction set
Any 64-bit Linux Any x86 64-bit 1-1.5x Non-vector
Linux 2.6 or newer Penryn (Core 2 or newer) 1.3-1.8x SSE 4.1
Linux 2.6.30 or newer SandyBridge (i3, i5, i7, Xeon E3, E5, E7 or newer) 2-2.5x AVX

To find out exactly which processor is in your machine, you can run this command in the terminal:

$ cat /proc/cpuinfo | grep "model name"                                                                                    
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz
model name  : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz

In this example, the machine has 4 cores (8-threads), so you see the answer 8 times. With the model name (here i7-2600) you can look up your hardware's relevant capabilities in the Wikipedia page on vector extensions.

Alternatively, Intel has provided us with some links to lists of processors categorized by architecture, in which you can look up your hardware:

Penryn processors


Sandy Bridge processors


Finally, a few notes to clarify some concepts regarding Linux kernels vs. distributions and processors vs. architectures:

  • SandyBridge and Penryn are microarchitectures; essentially, these are sets of instructions built into the CPU. Core 2, core i3, i4, i7, Xeon e3, e5, e7 are the processors that will implement a specific architecture to make use of the relevant improvements (see table above).

  • The Linux kernel has no connection with Linux distribution (e.g. Ubuntu, RedHat etc). Any distribution can use any kernel they want. There are "default kernels" shipped with each distribution, but that's beyond the scope of this article to cover (there are at least 300 Linux distributions out there). But you can always install whatever kernel version you want.

  • The kernel version 2.6.30 was released in 2009, so we expect every sane person or IT out there to be using something better than this.

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Better late than never, here is the now-traditional "Highlights" document for GATK version 3.0, which was released two weeks ago. It will be a very short one since we've already gone over the new features in detail in separate articles --but it's worth having a recap of everything in one place. So here goes.

Work smarter, not harder

We are delighted to present our new Best Practices workflow for variant calling in which multisample calling is replaced by a winning combination of single-sample calling in gVCF mode and joint genotyping analysis. This allows us to both bypass performance issues and solve the so-called "N+1 problem" in one fell swoop. For full details of why and how this works, please see this document. In the near future, we will update our Best Practices page to make it clear that the new workflow is now the recommended way to go for calling variants on cohorts of samples. We've already received some pretty glowing feedback from early adopters, so be sure to try it out for yourself!

Jumping on the RNAseq bandwagon

All the cool kids were doing it, so we had to join the party. It took a few months of experimentation, a couple of new tools and some tweaks to the HaplotypeCaller, but you can now call variants on RNAseq with GATK! This document details our Best Practices recommendations for doing so, along with a non-trivial number of caveats that you should keep in mind as you go.

Goodbye to ReduceReads

Nice try, but no. This tool is obsolete now that we have the gVCF/reference model pipeline (see above). Note that this means that GATK 3.0 will not support BAM files that were processed using ReduceReads!

Changes for developers

We've switched the build system from Ant to Maven, which should make it much easier to use GATK as a library against which you can develop your own tools. And on a related note, we're also making significant changes to the internal structure of the GATK codebase. Hopefully this will not have too much impact on external projects, but there will be a doc very shortly describing how the new build system works and how the codebase is structured.

Hardware optimizations held for 3.1

For reasons that will be made clear in the near future, we decided to hold the previously announced hardware optimizations until version 3.1, which will be released very soon. Stay tuned!

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Better late than never, here are the highlights of the most recent version release, GATK 2.8. This should be short and sweet because as releases go, 2.8 is light on new features, and is best described as a collection of bug fixes, which are all* dutifully listed in the corresponding release notes document. That said, two of the changes we've made deserve some additional explanation.

* Up to now (this release included) we have not listed updates/patches to Queue in the release notes, but will start doing so from the next version onward.

VQSR & bad variants: no more guessing games

In the last release (2.7, for those of you keeping score at home) we trumpeted that the old -percentBad argument of VariantRecalibrator had been replaced by the shiny new -numBad argument, and that this was going to be awesome for all sorts of good reasons, improve stability and whatnot. Weeeeeeell it turned out that wasn't quite the case. It worked really well on the subset of analyses that we tested it on initially, but once we expanded to different datasets (and the complaints started rolling in on the forum) we realized that it actually made things worse in some cases because the default value was less appropriate than what -percentBad would have produced. This left people guessing as to what value would work for their particular dataset, with a great big range to choose from and very little useful information to assist in the choice.

So, long story short, we (and by "we" I mean Ryan) built in a new function that allows the VariantRecalibrator to determine for itself the amount of variants that is appropriate to use for the "bad" model depending on the data. So the short-lived -numBad argument is gone too, replaced by... nothing. No new argument to specify; just let the VariantRecalibrator do its thing.

Of course if you really want to, you can override the default behavior and tweak the internal thresholds. See the tool doc here; and remember that a good rule of thumb is that if you can't figure out which arguments are involved based on that doc, you probably shouldn't be messing with this advanced functionality.

Reference calculation model

This is still a rather experimental feature, so we're still making changes as we go. The two big changes worth mentioning here are that you can now run this on reduced reads, and that we've changed the indexing routine to optimize the compression level. The latter shouldn't have any immediate impact on normal users, but it was necessary for a new feature project we've been working on behind the scenes (the single-sample-to-joint-discovery pipeline we have been alluding to in recent forum discussions). The reason we're mentioning it now is that if you use -ERC GVCF output, you'll need to specify a couple of new arguments as well (-variant_index_type LINEAR and -variant_index_parameter 128000, with those exact values). This useful little fact didn't quite make it into the documentation before we released, and not specifying them leads to an error message, so... there you go. No error message for you!

What's up, doc?

That's all for tool changes. In addition to those, we have made a number of corrections in the tool documentation pages, updated the Best Practices (mostly layout, tiny bit of content update related to the VQSR -numBad deprecation) and made some minor changes to the website, e.g. updated the list of publications that cite the GATK and improved the Guide index somewhat (but that's still a work in progress).

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Yay, August is over! Goodbye steamy hot days, hello mild temperatures and beautiful leaf-peeping season. We hope you all had a great summer (in the Northern hemisphere at least) and caught a bit of a vacation. For our part, we've been chained to our desks the whole time!

Well, not really, but we've got a feature-rich release for you nonetheless. Lots of new things; not all of them fully mature, so heed the caveats on the experimental features! We've also made some key improvements to VQSR that we're very excited about, some bug fixes to various tools of course, and a new way to boost calling performance. Full list in the release notes as usual, and highlights below.

Estimating the confidence of reference calls

When UnifiedGenotyper and HaplotypeCaller emit variant calls, they tell you how confident you can be that the variants are real. But how do you know how confident to be that the rest are reference, i.e. non-variant? It's actually a pretty hard problem… and this is our answer:

  • For HaplotypeCaller, we’ve developed a full-on reference model that produces reference confidence scores. To use it, you need to enable the --emitRefConfidence mode. This mode is a little bit complicated so be sure you read the method article before you try to use it.

  • For UnifiedGenotyper, we don’t have a completely fleshed-out model, but we’ve added the -allSitePLs argument which, in combination with the EMIT_ALL_SITES output mode, will enable calculation of PLs for all sites, including reference. This will give a measure of reference confidence and a measure of which alt alleles are more plausible (if any). Note that this only works with the SNP calling model. Again, this is not as good or as complete as the reference model in HaplotypeCaller, so we urge you to use HaplotypeCaller for this unless you really need to use UnifiedGenotyper.

These are two highly experimental features; they work in our tests, but your mileage may vary, so please examine your results carefully. We welcome your feedback!

Modelling PCR errors that cause indel artifacts

A common problem in calling indels is that you get false positives that are associated with PCR slippage around short tandem repeats (especially homopolymers). Until we can all switch to PCR-free amplification, we're stuck with this issue. So we thought it would be nice to be able to model this type of error and mitigate its impact on our indel calls. The new --pcr_indel_model argument allows the HaplotypeCaller to use a new feature called the PCR indel model to weed out false positive indels more or less aggressively depending on how much you care about sensitivity vs. specificity.

This feature too is highly experimental, so play with it at your own risk. And stay tuned, because we've already got some ideas on how to improve it further.

VariantRecalibrator gets an oil change and free tire rotation

Variant recalibration is one of the most challenging parts of the Best Practices workflow, and not just for users! We've been wrestling with some of its internal machinery to produce better, more consistent modeling results, especially with call sets that are on the lower end of the size scale.

One of the breakthroughs we made was separating the parameters for the positive and negative training models. You know (or should know) that the VariantRecalibrator builds two separate models: one to model what "good" variants (i.e. true positives) look like (the positive model), and one to model what "bad" variants (i.e. false positives) look like (the negative model). Until now, we applied parameters the same way to both, but we've now realized that it makes more sense to treat them differently.

Because of how relative amounts of good and bad variants tend to scale differently with call set size, we also realized it was a bad idea to have the selection of bad variants be based on a percentage (as it has been until now) and instead switched it to a hard number. You can change this setting with the --numBadVariants argument, which replaces the now-deprecated --percentBadVariants argument.

Finally, we also found that the order of annotations matters. Now, instead of applying the annotation dimensions to the training model in the order that they were specified at the command line, VariantRecalibrator first reorders them based on their standard deviation. This stabilizes the training model and produces much more consistent results.

New arguments and tools for finer control of data

Some of you have been clamoring for more flexibility in handling individual BAM files and samples without losing the convenience of processing them in batches. In response, we've added the following:

  • For general GATK use, the -sample_rename_mapping_file engine argument allows you to rename samples on-the-fly at runtime. It takes a file that maps bam files to sample names. Note that this does require that your BAM files contain single samples only, although multiple read groups are allowed.

  • For variant calling, the -onlyEmitSamples argument allows you to tell the UnifiedGenotyper to only emit calls for specific samples among a cohort that you're calling in multisample mode, without emitting the calls for the rest of the cohort. Keep in mind however that the calculations will still be made on the entire cohort, and the annotation values emitted for those calls will reflect that.

  • For VQSR, the --excludeFiltered flag tells the ApplyRecalibration tool not to emit sites that are filtered out by recalibration (i.e. do not write them to file).

And some of you went ahead and added the features you wanted yourselves!

  • Yossi Farjoun contributed a patch to enable allele-biased downsampling with different per-sample values for the HaplotypeCaller, emulating the equivalent functionality that was already available in the UnifiedGenotyper.

  • Louis Bergelson contributed a new read filter, LibraryReadFilter, which allows you to use only reads from a specific library in your analysis. This is the opposite (and somewhat more specific) functionality compared to the existing engine argument, --read_group_black_list , which allows you to exclude read groups based on specific tags (including but not limited to LB).

Better diagnostics when things go wrong

We have a new diagnostic tool, QualifyMissingIntervals, that allows you to collect metrics such as GC content, mapping quality etc. for a list of intervals of interest. This is something you'd typically want to use if you found (through other tools) that you're missing calls in certain intervals, and you want to find out what's going wrong in those regions.

FPGA support for the pairHMM model in UG and HC

Finally, those of you who have access to more sophisticated computing platforms, heads up! Version 2.7 comes with a version of the PairHMM algorithm (aka the bit that takes forever to run in HaplotypeCaller) that is optimized for running on FPGA chips. Credit goes to the fine folks at Convey Computer and Green Mountain Computing Systems who teamed up to develop this optimized version of the PairHMM, with a little help from our very own Tech Dev team. We're told further optimizations may be in store; in the meantime, they're seeing up to 300-fold speedups of HaplotypeCaller runs on Convey's platform. Not bad!

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It's finally summer here in New England -- time for cave-dwelling developers to hit the beach and do the lobster dance (those of us who don't tan well anyway). We leave you with a new version of the GATK that includes a new(ish) plotting tool, some more performance improvements to the callers, a lot of feature tweaks and quite a few bug fixes. Be sure to check out the full list in the 2.6 Release Notes.

Highlights are below as usual, enjoy. There's one thing that we need to point out with particular emphasis: we have moved to Java 7, so you may need to update your system's Java version. Full explanation at the end of this document because it's a little long, but be sure to read it.

New(ish) plotting tool for Base Recalibration results

GATK old-timers may remember a tool called AnalyzeCovariates, which was part of the BQSR process in 1.x versions, many moons ago. Well, we've resurrected it to take over the plotting functionality of the BaseRecalibrator, to make it easier and faster to plot and compare the results of base recalibration. This also prevents issues with plot generation in scatter-gather mode. We'll update our docs on the BQSR workflow in the next few days, but in the meantime you can find full details of how to use this tool here.

HaplotypeCaller now so sensitive, it cries at the movies

We know you don't want to miss a single true variant, so for this release, we've put a lot of effort into making the HaplotypeCaller more sensitive. And it's paying off: in our tests, the HaplotypeCaller is now more sensitive than the UnifiedGenotyper for calling both SNPs and indels when run over whole genome datasets.

[graph to illustrate, coming soon]

UnifiedGenotyper: not out of the race yet

You might think all our focus is on improving the HaplotypeCaller these days; you would be wrong. The UnifiedGenotyper is still essential for calling large numbers of samples together, for dealing with exotic ploidies, and for calling pooled samples. So we've given it a turbo boost that makes it go twice as fast for calling indels on multiple samples.

The key change here is the updated Hidden Markov Model used by the UG. You can see on the graph that as the number of exomes being called jointly increases, the new HMM keeps runtimes down significantly compared to the old HMM.

Version tracking in the VCF header

Don’t you hate it when you go back to a VCF you generated some months ago, and you have no idea which version of GATK you used at the time? (And yes, versions matter. Sometimes a lot.) We sure do, so we added a function to add the GATK version number in the header of the VCFs generated by GATK.

Migration to Java 7

Speaking of software versions... As you probably know, the GATK runs on Java -- specifically, until now, version 6 of the Runtime Environment (which translates to version 1.6 if you ask java -version at the command prompt). But the Java language has been evolving under our feet; version 7 has been out and stable for some time now, and version 8 is on the horizon. We were happy as clams with Java 6… but now, newer computers with recent OS versions ship with Java 7, and on MacOS X once you update the system it is difficult to go back to using Java 6. And since Java 7 is not fully backwards compatible, people have been running into version problems.

So, we have made the difficult but necessary decision to follow the tide, and migrate the GATK to Java 7. Starting with this release, GATK will now require Java 7 to run. If you try to run with Java 6, you will probably get an error like this:

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/broadinstitute/sting/gatk/CommandLineGATK : Unsupported major.minor version 51.0

If you're not sure what version of Java you are currently using, you can find out very easily by typing the following command:

java -version

which should return something like this:

java version "1.7.0_17"
Java(TM) SE Runtime Environment (build 1.7.0_17-b02)
Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode)

If not, you'll need to update your java version. If you have any difficulty doing this, please don’t ask us in the forum -- you’ll get much better, faster help if you ask your local IT department.

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This is going to be a short one, folks. The 2.5 release is pretty much all about bug fixes, with a couple of exceptions that we'll cover below.

Bug fixes

Remember how we said that version 2.4 was going to be the least buggy ever? Well, that might have been a bit optimistic. We had a couple of stumpers in there -- and a flurry of little ones that were probably not novel (i.e. not specific to version 2.5) but finally bubbled up to the surface. We're not going to go over the bug fixes in detail, since the release notes include a comprehensive list. Basically, those are all fixed.

Actual features!

Well, not exactly new features, but noteworthy improvements to existing tools.

- ReduceReads turns the squeeze dial up to eleven

In addition to countless bug fixes, we've made drastic improvements to ReduceReads' compression algorithm, so you can now achieve much better compression rates without compromising on the retention of informative data. Keep in mind of course that as always, you'll see much bigger gains on certain types of data sets -- the higher the coverage in your original BAM files, the bigger the savings in file size and performance of the downstream tools.

- HaplotypeCaller is faster and more accurate! No, really!

We say this every time, and every time it's true: we've made some more improvements to the HaplotypeCaller that make it faster and more accurate. Well, it's still slower than the UnifiedGenotyper, in case you were going to ask (of course you were). But on the accuracy front, we say this without reservation or caveat: HC is now just as accurate as the UG for calling SNPs, and it is in a league of its own for calling indels. If you are even remotely interested in indels you should absolutely take it out for a spin. Go. Now.

- DiagnoseTargets, all grown up

Say goodbye to the mood swings and the pimples; it looks like this tool's awkward teenager phase is finally over. We've entirely reworked how DiagnoseTargets functions so it now uses a plugin system, which we think is much more convenient. This plugin system will be explained in detail in a forthcoming documentation article.

- Functional annotation recovers some functionality

You may be aware that we had imposed a freeze of sorts on the annotation database version that could be used with the snpEff annotation. Well, we're happy to report that the author of the snpEff software package has made some significant upgrades, including a feature called GATK compatibility mode. As a result there is no longer any version constraint. We'll be updating our documentation on using snpEff with GATK soon (-ish), but in the meantime, feel free to go forth and annotate away. Just make sure to consult the snpEff manual for relevant information on using it with GATK.

Deprecation alerts

Even as the dev team giveth, the dev team taketh away.

A few annotations were removed from the VariantAnnotator stables (as listed in the release notes), mainly because they didn't work properly. With all the caveats about how GATK is research software, we're still committed to providing quality tools that do something close to what they're advertised to do, at the bare minimum. If something doesn't fulfill that requirement, it's out.

We've also disabled the auto-generation of fai/dict files for fasta references. I can hear some of you groaning all the way from here. Yes, it was convenient -- but far too buggy. Come on people, it's a one-liner using Picard. Oh, and we're no longer allowing the use of compressed (.gz) references either -- also too buggy. The space savings were simply not worth the headaches.

Comments (7)


Release version 2.3 is the last before the winter holidays, so we've done our best not to put in anything that will break easily. Which is not to say there's nothing important - this release contains a truckload of feature tweaks and bug fixes (see the release notes in the next tab for full list). And we do have one major new feature for you: a brand-spanking-new downsampler to replace the old one.

Feature improvement highlights

- Sanity check for mis-encoded quality scores

It has recently come to our attention that some datasets are not encoded in the standard format (Q0 == ASCII 33 according to the SAM specification, whereas Illumina encoding starts at ASCII 64). This is a problem because the GATK assumes that it can use the quality scores as they are. If they are in fact encoded using a different scale, our tools will make an incorrect estimation of the quality of your data, and your analysis results will be off. To prevent this from happening, we've added a sanity check of the quality score encodings that will abort the program run if they are not standard. If this happens to you, you'll need to run again with the flag --fix_misencoded_quality_scores (-fixMisencodedQuals). What will happen is that the engine will simply subtract 31 from every quality score as it is read in, and proceed with the corrected values. Output files will include the correct scores where applicable.

- Overall GATK performance improvement

Good news on the performance front: we eliminated a bottleneck in the GATK engine that increased the runtime of many tools by as much as 10x, depending on the exact details of the data being fed into the GATK. The problem was caused by the internal timing code invoking expensive system timing resources far too often. Imagine you looked at your watch every two seconds -- it would take you ages to get anything done, right? Anyway, if you see your tools running unusually quickly, don't panic! This may be the reason, and it's a good thing.

- Co-reducing BAMs with ReduceReads (Full version only)

You can now co-reduce separate BAM files by passing them in with multiple -I or as an input list. The motivation for this is that samples that you plan to analyze together (e. g. tumor-normal pairs or related cohorts) should be reduced together, so that if a disagreement is triggered at a locus for one sample, that locus will remain unreduced in all samples. You will therefore conserve the full depth of information for later analysis of that locus.

Downsampling, overhauled

The downsampler is the component of the GATK engine that handles downsampling, i. e. the process of removing a subset of reads from a pileup. The goal of this process is to speed up execution of the desired analysis, particularly in genome regions that are covered by excessive read depth.

In this release, we have replaced the old downsampler with a brand new one that extends some options and performs much better overall.

- Downsampling to coverage for read walkers

The GATK offers two different options for downsampling:

  • --downsample_to_coverage (-dcov) enables you to set the maximum amount of coverage to keep at any position
  • --downsample_to_fraction (-dfrac) enables you to remove a proportional amount of the reads at any position (e. g. take out half of all the reads)

Until now, it was not possible to use the --downsample_to_coverage (-dcov) option with read walkers; you were limited to using --downsample_to_fraction (-dfrac). In the new release, you will be able to downsample to coverage for read walkers.

However, please note that the process is a little different. The normal way of downsampling to coverage (e. g. for locus walkers) involves downsampling over the entire pileup of reads in one take. Due to technical reasons, it is still not possible to do that exact process for read walkers; instead the read-walker-compatible way of doing it involves downsampling within subsets of reads that are all aligned at the same starting position. This different mode of operation means you shouldn't use the same range of values; where you would use -dcov 100 for a locus walker, you may need to use -dcov 10 for a read walker. And these are general estimates - your mileage may vary depending on your dataset, so we recommend testing before applying on a large scale.

- No more downsampling bias!

One important property of the downsampling process is that it should be as random as possible to avoid introducing biases into the selection of reads that will be kept for analysis. Unfortunately our old downsampler - specifically, the part of the downsampler that performed the downsampling to coverage - suffered from some biases. The most egregious problem was that as it walked through the data, it tended to privilege more recently encountered reads and displaced "older" reads. The new downsampler no longer suffers from these biases.

- More systematic testing

The old downsampler was embedded in the engine code in a way that made it hard to test in a systematic way. So when we implemented the new downsampler, we reorganized the code to make it a standalone engine component - the equivalent of promoting it from the cubicle farm to its own corner office. This has allowed us to cover it much better with systematic tests, so we have better assessment of whether it's working properly.

- Option to revert to the old downsampler

The new downsampler is enabled by default and we are confident that it works much better than the old one. BUT as with all brand-spanking-new features, early adopters may run into unexpected rough patches. So we're providing a way to disable it and use the old one, which is still in the box for now: just add -use_legacy_downsampler to your command line. Obviously if you use this AND -dcov with a read walker, you'll get an error, since the old downsampler can't downsample to coverage for read walkers.

 Note: There are no version highlights available for versions earlier than 2.2.

These are the release notes issued for all major and minor version releases (for example, 2.2). At this time, we do not provide release notes for subversion changes (for example, 2.2-12) but you can view the latest changes in the Change log (next tab).
Comments (2)

GATK 3.3 was released on October 23, 2014. Itemized changes are listed below. For more details, see the user-friendly version highlights.

Haplotype Caller

  • Improved the accuracy of dangling head merging in the HC assembler (now enabled by default).
  • Physical phasing information is output by default in new sample-level PID and PGT tags.
  • Added the --sample_name argument. This is a shortcut for people who have multi-sample BAMs but would like to use -ERC GVCF mode with a particular one of those samples.
  • Support added for generalized ploidy. The global ploidy is specified with the -ploidy argument.
  • Fixed IndexOutOfBounds error associated with tail merging.

Variant Recalibrator

  • New --ignore_all_filters option. If specified, the variant recalibrator will ignore all input filters and treat sites as unfiltered.


  • Support added for generalized ploidy. The global ploidy is specified with the -ploidy argument.
  • Bug fix for the case when we assumed ADs were in the same order if the number of alleles matched.
  • Changed the default GVCF GQ Bands from 5,20,60 to be 1..60 by 1s, 60...90 by 10s and 99 in order to give finer resolution.
  • Bug fix in the exact model when calling multi-allelic variants. QUAL field is now more accurate.

RNAseq analysis

  • Bug fixes for working with unmapped reads.


  • New annotation for low- and high-confidence possible de novos (only annotates biallelics).
  • FamilyLikelihoodsUtils now add joint likelihood and joint posterior annotations.
  • Restricted population priors based on discovered allele count to be valid for 10 or more samples.


  • Fixed rare bug triggered by hash collision between sample names.


  • Updated the --keepOriginalAC functionality in SelectVariants to work for sites that lose alleles in the selection.


  • Read groups that are excluded by sample_name, platform, or read_group arguments no longer appear in the header.
  • The performance penalty associated with filtering by read group has been essentially eliminated.


  • StrandOddsRatio is now a standard annotation that is output by default.
  • We used to output zero for FS if there was no data available at a site, now we omit FS.
  • Extensive rewrite of the annotation documentation.


  • Fixed Queue bug with bad localhost addresses.
  • Fixed issue related to spaces in job names that were fine in GridEngine 6 but break in (Son of) GE8.
  • Improved scatter contigs algorithm to be fairer when splitting many contigs into few parts (contributed by @smowton)


  • We now generate PHP files instead of HTML.
  • We now output a JSON version of the tool documentation that can be used to generate wrappers for GATK commands.


  • Output arguments --no_cmdline_in_header, --sites_only, and --bcf for VCF files, and --bam_compression, --simplifyBAM, --disable_bam_indexing, and --generate_md5 for BAM files moved to the engine level.
  • htsjdk updated to version 1.120.1620
Comments (13)

GATK 3.2 was released on July 14, 2014. Itemized changes are listed below. For more details, see the user-friendly version highlights.

We also want to take this opportunity to thank super-user Phillip Dexheimer for all of his excellent contributions to the codebase, especially for this release.

Haplotype Caller

  • Various improvements were made to the assembly engine and likelihood calculation, which leads to more accurate genotype likelihoods (and hence better genotypes).
  • Reads are now realigned to the most likely haplotype before being used by the annotations, so AD and DP will now correspond directly to the reads that were used to generate the likelihoods.
  • The caller is now more conservative in low complexity regions, which significantly reduces false positive indels at the expense of a little sensitivity; mostly relevant for whole genome calling.
  • Small performance optimizations to the function to calculate the log of exponentials and to the Smith-Waterman code (thanks to Nigel Delaney).
  • Fixed small bug where indel discovery was inconsistent based on the active-region size.
  • Removed scary warning messages for "VectorPairHMM".
  • Made VECTOR_LOGLESS_CACHING the default implementation for PairHMM.
  • When we subset PLs because alleles are removed during genotyping we now also subset the AD.
  • Fixed bug where reference sample depth was dropped in the DP annotation.

Variant Recalibrator

  • The -mode argument is now required.
  • The plotting script now uses the theme instead of opt functions to work with recent versions of the ggplot2 R library.


  • The plotting script now uses the theme instead of opt functions to work with recent versions of the ggplot2 R library.

Variant Annotator

  • SB tables are created even if the ref or alt columns have no counts (used in the FS and SOR annotations).

Genotype GVCFs

  • Added missing arguments so that now it models more closely what's available in the Haplotype Caller.
  • Fixed recurring error about missing PLs.
  • No longer pulls the headers from all input rods including dbSNP, rather just from the input variants.
  • --includeNonVariantSites should now be working.

Select Variants

  • The dreaded "Invalid JEXL expression detected" error is now a kinder user error.

Indel Realigner

  • Now throws a user error when it encounters reads with I operators greater than the number of read bases.
  • Fixed bug where reads that are all insertions (e.g. 50I) were causing it to fail.


  • Now computes posterior probabilities only for SNP sites with SNP priors (other sites have flat priors applied).
  • Now computes genotype posteriors using likelihoods from all members of the trio.
  • Added annotations for calling potential de novo mutations.
  • Now uses PP tag instead of GP tag because posteriors are Phred-scaled.

Cat Variants

  • Can now process .list files with -V.
  • Can now handle BCF and Block-Compressed VCF files.

Validate Variants

  • Now works with gVCF files.
  • By default, all strict validations are performed; use --validationTypeToExclude to exclude specific tests.


  • Now use '--use_IUPAC_sample sample_name' to specify which sample's genotypes should be used for the IUPAC encoding with multi-sample VCF files.


  • Refactored maven directories and java packages replacing "sting" with "gatk".
  • Extended on-the-fly sample renaming feature to VCFs with the --sample_rename_mapping_file argument.
  • Added a new read transformer that refactors NDN cigar elements to one N element.
  • Now a Tabix index is created for block-compressed output formats.
  • Switched outputRoot in SplitSamFile to an empty string instead of null (thanks to Carlos Barroto).
  • Enabled the AB annotation in the reference model pipeline (thanks to John Wallace).
  • We now check that output files are specified in a writeable location.
  • We now allow blank lines in a (non-BAM) list file.
  • Added legibility improvements to the Progress Meter.
  • Allow for non-tab whitespace in sample names when performing on-the-fly sample-renaming (thanks to Mike McCowan).
  • Made IntervalSharder respect the IntervalMergingRule specified on the command line.
  • Sam, tribble, and variant jars updated to version 1.109.1722; htsjdk updated to version 1.112.1452.
Comments (0)

GATK 3.1 was released on March 18, 2014. Highlights are listed below. Read the detailed version history overview here:

Haplotype Caller

  • Added new capabilities to the Haplotype Caller to use hardware-based optimizations. Can be enabled with --pair_hmm_implementation VECTOR_LOGLESS_CACHING. Please see the 3.1 Version Highlights for more details about expected speed ups and some background on the collaboration that made these possible.
  • Fixed bugs in computing the weights of edges in the assembly graph. This was causing bad genotypes to be output when running the Haplotype Caller over multiple samples simultaneously (as opposed to creating gVCFs in the new recommended pipeline, which was working as expected).

Variant Recalibrator

  • Fixed issue where output could be non-deterministic with very large data sets.


  • Fixed several bugs where bad input were causing the tool to crash instead of gracefully exiting with an error message.


  • RandomlySplitVariants can now output splits comprised of more than 2 output files.
  • FastaAlternateReferenceMaker can now output heterozygous sites using IUPAC ambiguity encoding.
  • Picard, Tribble, and Variant jars updated to version 1.109.1722.
Comments (2)

GATK 3.0 was released on March 5, 2014. Highlights are listed below. Read the detailed version history overview here:

One important change for those who prefer to build from source is that we now use maven instead of ant. See the relevant documentation for building the GATK with our new build system.


  • This is a new GATK tool to be used for variant calling in RNA-seq data. Its purpose is to split reads that contain N Cigar operators (due to a limitation in the GATK that we will eventually handle internally) and to trim (and generally clean up) imperfect alignments.

Haplotype Caller

  • Fixed bug where dangling tail merging in the assembly graph occasionally created a cycle.
  • Added experimental code to retrieve dangling heads in the assembly graph, which is needed for calling variants in RNA-seq data.
  • Generally improved gVCF output by making it more accurate. This includes many updates so that the single sample gVCFs can be accurately genotyped together by GenotypeGVCFs.
  • Fixed a bug in the PairHMM class where the transition probability was miscalculated resulting in probabilities larger than 1.
  • Fixed bug in the function to find the best paths from an alignment graph which was causing bad genotypes to be emitted when running with multiple samples together.


  • This is a new GATK tool to be used in the Haplotype Caller pipeline with large cohorts. Its purpose is to combine any number of gVCF files into a single merged gVCF. One would use this tool for hierarchical merges of the data when there are too many samples in the project to throw at all at once to GenotypeGVCFs.


  • This is a new GATK tool to be used in the Haplotype Caller pipeline. Its purpose is to take any number of gVCF files and to genotype them in order to produce a VCF with raw SNP and indel calls.


  • This is a new GATK tool that might be useful to some. Given a VCF file, this tool will generate simulated reads that support the variants present in the file.

Unified Genotyper

  • Fixed bug when clipping long reads in the HMM; some reads were incorrectly getting clipped.

Variant Recalibrator

  • Added the capability to pass in a single file containing a list of VCFs (must end in ".list") instead of having to enumerate all of the files on the command-line. Duplicate entries are not allowed in the list (but the same file can be present in separate lists).

Reduce Reads

  • Removed from the GATK. It was a valiant attempt, but ultimately we found a better way to process large cohorts. Reduced BAMs are no longer supported in the GATK.

Variant Annotator

  • Improved the FisherStrand (FS) calculation when used in large cohorts. When the table gets too large, we normalize it down to values that are more reasonable. Also, we don't include a particular sample's contribution unless we observe both ref and alt counts for it. We expect to improve on this even further in a future release.
  • Improved the QualByDepth (QD) calculation when used in large cohorts. Now, when the AD annotation is present for a given genotype then we only use its depth for QD if the variant depth > 1. Note that this only works in the gVCF pipeline for now.
  • In addition, fixed the normalization for indels in QD (which was over-penalizing larger events).

Combine Variants

  • Added the capability to pass in a single file containing a list of VCFs (must end in ".list") instead of having to enumerate all of the files on the command-line. Duplicate entries are not allowed in the list (but the same file can be present in separate lists).

Select Variants

  • Fixed a huge bug where selecting out a subset of samples while using multi-threading (-nt) caused genotype-level fields (e.g. AD) to get swapped among samples. This was a bad one.
  • Fixed a bug where selecting out a subset of samples at multi-allelic sites occasionally caused the alternate alleles to be re-ordered but the AD values were not updated accordingly.


  • Fixed bug where it wasn't checking for underflow and occasionally produced bad likelihoods.
  • It no longer strips out the AD annotation from genotypes.
  • AC/AF/AN counts are updated after fixing genotypes.
  • Updated to handle cases where the AC (and MLEAC) annotations are not good (e.g. they are greater than AN somehow).

Indel Realigner

  • Fixed bug where a realigned read can sometimes get partially aligned off the end of the contig.

Read Backed Phasing

  • Updated the tool to use the VCF 4.1 framework for phasing; it now uses HP tags instead of '|' to convey phase information.


  • Thanks to Phillip Dexheimer for several Queue related fixes and patches.
  • Thanks to Nicholas Clarke for patches to the timer which occasionally had negative elapsed times.
  • Providing an empty BAM list no results in a user error.
  • Fixed a bug in the gVCF writer where it was dropping the first few reference blocks at the beginnings of all but the first chromosome. Also, several unnecessary INFO field annotations were dropped from the output.
  • Logger output now goes to STDERR instead of STDOUT.
  • Picard, Tribble, and Variant jars updated to version 1.107.1683.
Comments (2)

GATK 2.8 was released on December 6, 2013. Highlights are listed below. Read the detailed version history overview here:

Note that this release is relatively smaller than previous ones. We are working hard on some new tools and frameworks that we are hoping to make available to everyone for our next release.

Unified Genotyper

  • Fixed bug where indels in very long reads were sometimes being ignored and not used by the caller.

Haplotype Caller

  • Improved the indexing scheme for gVCF outputs using the reference calculation model.
  • The reference calculation model now works with reduced reads.
  • Fixed bug where an error was being generated at certain homozygous reference sites because the whole assembly graph was getting pruned away.
  • Fixed bug for homozygous reference records that aren't GVCF blocks and were being treated incorrectly.

Variant Recalibrator

  • Disable tranche plots in INDEL mode.
  • Various VQSR optimizations in both runtime and accuracy. Some particular details include: for very large whole genome datasets with over 2M variants overlapping the training data randomly downsample the training set that gets used to build; annotations are ordered by the difference in means between known and novel instead of by their standard deviation; removed the training set quality score threshold; now uses 2 gaussians by default for the negative model; numBad argument has been removed and the cutoffs are now chosen by the model itself by looking at the LOD scores.

Reduce Reads

  • Fixed bug where mapping quality was being treated as a byte instead of an int, which caused high MQs to be treated as negative.

Diagnose Targets

  • Added calculation for GC content.
  • Added an option to filter the bases based on their quality scores.

Combine Variants

  • Fixed bug where annotation values were parsed as Doubles when they should be parsed as Integers due to implicit conversion; submitted by Michael McCowan.

Select Variants

  • Changed the behavior for PL/AD fields when it encounters a record that has lost one or more alternate alleles: instead of stripping them out these fields now get fixed.


  • SplitSamFile now produces an index with the BAM.
  • Length metric updates to QualifyMissingIntervals.
  • Provide close methods to clean up resources used while creating AlignmentContexts from BAM file regions; submitted by Brad Chapman.
  • Picard jar updated to version 1.104.1628.
  • Tribble jar updated to version 1.104.1628.
  • Variant jar updated to version 1.104.1628.
Comments (2)

GATK 2.7 was released on August 21, 2013. Highlights are listed below. Read the detailed version history overview here:

Reduce Reads

  • Changed the underlying convention of having unstranded reduced reads; instead there are now at least 2 compressed reads at every position, one for each strand (forward and reverse). This allows us to maintain strand information that is useful for downstream filtering.
  • Fixed bug where representative depths were arbitrarily being capped at 127 (instead of the expected 255).
  • Fixed bug where insertions downstream of a variant region weren't triggering a stop to the compression.
  • Fixed bug when using --cancer_mode where alignments were being emitted out of order (and causing the tool to fail).

Unified Genotyper

  • Added --onlyEmitSamples argument that, when provided, instructs that caller to emit only the selected samples into the VCF (even though the calling is performed over all samples present in the provided bam files).
  • FPGA support was added to the underlying HMM that is automatically used when the appropriate hardware is available on the machine.
  • Added a (very) experimental argument (allSitePLs) that will have the caller emit PLs for all sites (including reference sites). Note that this does not give a fully accurate reference model because it models only SNPs. Full a proper handling of the reference model, please use the Haplotype Caller.

Haplotype Caller

  • Added a still somewhat experimental PCR indel error model to the Haplotype Caller. By default this modeling is turned on and is very useful for removing false positive indel calls associated with PCR slippage around short tandem repeats (esp. homopolymers). Users have the option (with the --pcr_indel_model argument) of turning it off or making it even more aggressive (at the expense of losing some true positives too).
  • Added the ability to emit accurate likelihoods for non-variant positions (i.e. what we call a "reference model" that incorporates indels as well as SNP confidences at every position). The output format can be either a record for every position or use the gVCF style recording of blocks. See the --emitRefConfidence argument for more details; note that this replaces the use of "--output_mode EMIT_ALL_SITES" in the HaplotypeCaller.
  • Improvements to the internal likelihoods that are generated by the Haplotype Caller. Specifically, this tool now uses a tri-state correction like the Unified Genotyper, corrects for overlapping read pairs (from the same underlying fragment), and does not run contamination removal (allele-biased downsampling) by default.
  • Several small runtime performance improvements were added (although we are still hard at work on larger improvements that will allow calling to scale to many samples; we're just not there yet).
  • Fixed bug in how adapter clipping was performed (we now clip only after reverting soft-clipped bases).
  • FPGA support was added to the underlying HMM that is automatically used when the appropriate hardware is available on the machine.
  • Improved the "dangling tail" recovery in the assembly algorithm, which allows for higher sensitivity in calling variants at the edges of coverage (e.g. near the ends of targets in an exome).
  • Added the ability to run allele-biased downsampling with different per-sample values like the Unified Genotyper (contributed by Yossi Farjoun).

Variant Annotator

  • Fixed bug where only the last -comp was being annotated at a site.

Indel Realigner

  • Fixed bug that arises because of secondary alignments and that was causing the tool not to update the alignment start of the mate when a read was realigned.

Phase By Transmission

  • Fixed bug where multi-allelic records were being completely dropped by this tool. Now they are emitted unphased.

Variant Recalibrator

  • General improvements to the Gaussian modeling, mostly centered around separating the parameters for the positive and negative training models.
  • The percentBadVariants argument has been replaced with the numBad argument.
  • Added mode to not emit (at all) variant records that are filtered out.
  • This tool now automatically orders the annotation dimensions by their standard deviation instead of the order they were specified on the command-line in order to stabilize the training and have it produce optimal results.
  • Fixed bug where the tool occasionally produced bad log10 values internally.


  • General performance improvements to the VCF reading code contributed by Michael McCowan.
  • Error messages are much less verbose and "scary."
  • Added a LibraryReadFilter contributed by Louis Bergelson.
  • Fixed the ReadBackedPileup class to represent mapping qualities as ints, not (signed) bytes.
  • Added the engine-wide ability to do on-the-fly BAM file sample renaming at runtime (see the documentation for the --sample_rename_mapping_file argument for more details).
  • Fixed bug in how the GATK counts filtered reads in the traversal output.
  • Added a new tool called Qualify Intervals.
  • Fixed major bug in the BCF encoding (the previous version was producing problematic files that were failing when trying to be read back into the GATK).
  • Picard/sam/tribble/variant jars updated to version 1.96.1534.
Comments (0)

GATK 2.6 was released on June 20, 2013. Highlights are listed below. Read the detailed version history overview here:

Important note: with this release the GATK has officially moved to using Java 7.

Reduce Reads

  • Small runtime performance improvements contributed by Michael McCowan.
  • Added fix for the "Removed too many insertions, header is now negative" bug.
  • Fixed bug that arises in multi-sample mode and causes the tool to crash.
  • Added --cancer_mode argument to force the user to explicitly enable multi-sample mode.

Unified Genotyper

  • Runtime performance improvements when calling indels; calling indels in a single sample is almost 2x faster in our tests.
  • Fixed bug for bad AD values in some cases.
  • Fixed bug for GENOTYPE_GIVEN_ALLELES mode where it silently fails to genotype indels in some cases.

Haplotype Caller

  • We have been working hard to reduce the number of false negatives (i.e. missed sites) for the Haplotype Caller and as such added a bunch of improvements to this tool. The sensitivity is now better than that of the Unified Genotyper is all of our whole genome tests for both SNPs and indels. Feel free to peruse the detailed version history for more information.
  • The Haplotype Caller now annotates IDs from dbSNP properly.
  • The Haplotype Caller now emits per-sample DP.
  • Fixed bug for bad AD values in some cases.
  • Fixed bug with error: "Only one of refStart or refStop must be < 0, not both" that arose from soft-clipped reads at the beginning of contigs.
  • Implemented a much improved version of GENOTYPE_GIVEN_ALLELES mode in the Haplotype Caller that works so much better.

Indel Realigner

  • Fixed bug where secondary alignments were not being handled correctly.

Genotype Concordance

  • Added an overall genotype concordance metric to the output.
  • Fixed a bug in the printout of molten data in how it treated the genotypes.

Diagnose Targets

  • Diagnose Targets now has an option to output missing intervals.
  • Fixed bug where sometimes intervals were emitted out of order.

Base Recalibrator

  • Fixed bug for reads with indel CIGAR operators (I or D) at the start/end of the read.
  • Introduced a new tool, AnalyzeCovariates, to generate the BQSR quality assessment plots as a separate step, instead of doing it through the BaseRecalibrator.

Combine Variants

  • We no longer add PASS to the FILTER field of unfiltered records.

Variant Annotator

  • The RMSMappingQuality annotation now works properly with reduced reads.
  • The various rank sum tests no longer use reduced reads in their calculations (because those reads do not represent distinct observations).
  • Fixed bug in the BaseQualityRankSumTest annotation where it was not actually using the base qualities.
  • Added a new annotation DepthPerSampleHC that is used by default in the HaplotypeCaller.


  • James Warren contributed a patch to have references with non-suffix ".fa" parse correctly.
  • We now emit the GATK version number in the header of VCFs that we produce.
  • Fixed bug in the up front downsampling used by the GATK: reduced reads are no longer allowed to be eliminated during downsampling.
  • dbSNP rsID matching is now smarter: variants are considered matching if they have the same reference allele and at least 1 common alternative allele.
  • We now warn users about using the GATK with RNA-seq data.
  • We now check that -compress arguments are within allowable range 0-9.
  • -rf ReassignMappingQuality can now be used to reassign mapping qualities to 60 before the engine filters them out with MappingQualityUnassigned.
  • Fixed bug where requesting gzip VCF output with multi-threading was causing the GATK to fail.
  • We now require a minimum -dcov value of 200 for Locus and ActiveRegion walkers when downsampling to coverage.
  • Zero-length and repeated cigar elements are collapsed down by default in the engine.
  • -ds option removed from PrintReads because it was redundant with the engine-level -dfrac argument.
  • Fixed bug where the --defaultBaseQualities argument didn't always work.
  • The engine now produces much more accurate read counts for Read traversals.
  • Count Reads now uses a Long instead of an Integer for counts to prevent overflows.
  • Locus Walkers now only try to clip adaptors when both reads of the pair are on opposite strands.
  • Fixed VCF issue where PLs were capped at 32767.
  • Picard/Tribble/Variant jars updated to version 1.91.1453.
Comments (4)

GATK 2.5 was released on April 30, 2013. Highlights are listed below. Read the detailed version history overview here:

Reduce Reads

  • DRASTIC improvements in the compression algorithm plus myriad bug fixes. Too many to list here; see detailed version history for more information.

Unified Genotyper

  • Fixed bug for indel calling with really long reads (assigning the wrong genotypes).
  • Automatic contamination fixing now works on reduced reads.
  • Fixed rare bug in the general ploidy SNP likelihood model when there are no informative reads in a pileup.
  • Fixed bug where haplotypes with 0 bases were being created.
  • Fixed problem where our internal PairHMM was generating positive likelihoods.

Haplotype Caller

  • Comprehensive performance improvements to the accuracy of calling both SNPs and indels; runtime is also much improved (but still slower than the Unified Genotyper; we expect it to be faster than UG in the next release though). See detailed version history for more information.
  • Fixed bug for calling on reduced reads (counts were not being assigned correctly).
  • Fixed problem where our internal PairHMM was generating positive likelihoods.
  • Can now write BAMs showing the assembled haplotypes.

Diagnose Targets

  • Significantly refactored this tool; it now works with a "plugin" system (see documentation for more information).
  • Fixed bug where LOW_MEDIAN_COVERAGE was output when no reads are covering the interval.
  • Fixed bug where intervals were skipped when they were not covered by any reads.

Base Recalibrator

  • Fixed the tool to work correctly with empty BQSR tables.
  • Fixed issue where Print Reads was running out of disk space when using the -BQSR option even for small bam files.
  • Fixed bug for RNA seq alignments with Ns.

Select Variants

  • Fixed bug where using the --exclude_sample_file argument was giving bad results.
  • Fixed bug when using the --keepOriginalAC argument which caused it to emit bad VCFs.
  • Fixed bug where maxIndelSize argument wasn't getting applied to deletions.

Variant Annotator

  • Added support for snpEff "GATK compatibility mode".
  • Can now list available annotations by doing java -cp GenomeAnalysisTK.jar
  • QualByDepth remaps QD values > 40 to a gaussian around 30.
  • Removed several deprecated annotations (AverageAltAlleleLength, MappingQualityZeroFraction, and TechnologyComposition) and others are no longer marked as experimental.

Variant Filtration

  • Don't allow users to specify keys and IDs that contain angle brackets or equals signs (which are not allowed in the VCF specification).
  • Added feature that allows one to filter sites outside of a given mask.

Left Align Variants

  • Renamed to LeftAlignAndTrimVariants.
  • Added ability to trim common bases in front of indels before left-aligning.
  • Added ability to split multiallelic records and then left align them.


  • We removed the auto-creation of fai/dict files for fasta references because it was too buggy.
  • Fixed bug where we could fail to find the intersection of unsorted/missorted interval lists.
  • Fixed @PG tag uniqueness issue with BAMs we were producing.
  • Fixed rare bug in GenotypeConcordance for multi-allelic sites.
  • Added check for reads without stored bases (i.e. that use '*') which we do not support.
  • Added support to reduce reads to CallableLoci.
  • Added a new walker to split MNPs into their allelic primitives (SNPs).
  • We no longer allow the use of compressed (.gz) references in the GATK.
  • Picard/Tribble/Variant jars updated to version 1.90.1442.
Comments (7)

GATK 2.4 was released on February 26, 2013. Highlights are listed below. Read the detailed version history overview here:

Important note 1 for this release: with this release comes an updated licensing structure for the GATK. Different files in our public repository are protected with different licenses, so please see the text at the top of any given file for details as to its particular license.

Important note 2 for this release: the GATK team spent a tremendous amount of time and engineering effort to add extensive tests for many of our core tools (a process that will continue into future releases). Unsurprisingly, as part of this process many small (and some not so small) bugs were uncovered during testing that we subsequently fixed. While we usually attempt to enumerate in our release notes all of the bugs fixed during a given release, that would entail quite a Herculean effort for release 2.4; so please just be aware that there were many smaller fixes that may be omitted from these notes.

Base Quality Score Recalibration

  • The underlying calculation of the recalibration has been improved and generalized so that the empirical quality is now calculated through a Bayesian estimate. This radically improves the accuracy in particular for bins with small numbers of observations.
  • Added many run time improvements so that this tool now runs much faster.
  • Print Reads writes a header when used with the -BQSR argument.
  • Added a check to make sure that BQSR is not being run on a reduced bam (which would be bad).
  • The --maximum_cycle_value argument can now be specified during the Print Reads step to prevent problems when running on bams with extremely long reads.
  • Fixed bug where reads with an existing BQ tag and soft-clipped bases could cause the tool to error out.

Unified Genotyper

  • Fixed the QUAL calculation for monomorphic (homozygous reference) sites (the math for previous versions was not correct).
  • Biased downsampling (i.e. contamination removal) values can now be specified as per-sample fractions.
  • Fixed bug where biased downsampling (i.e. contamination removal) was not being performed correctly in the presence of reduced reads.
  • The indel likelihoods calculation had several bugs (e.g. sometimes the log likelihoods were positive!) that manifested themselves in certain situations and these have all been fixed.
  • Small run time improvements were added.

Haplotype Caller

  • Extensive performance improvements were added to the Haplotype Caller. This includes run time enhancements (it is now much faster than previous versions) plus improvements in accuracy for both SNPs and indels. Internal assessment now shows the Haplotype Caller calling variants more accurately than the Unified Genotyper. The changes for this tool are so extensive that they cannot easily be enumerated in these notes.

Variant Annotator

  • The QD annotation is now divided by the average length of the alternate allele (weighted by the allele count); this does not affect SNPs but makes the calculation for indels much more accurate.
  • Fixed Fisher Strand annotation where p-values sometimes summed to slightly greater than 1.0.
  • Fixed Fisher Strand annotation for indels where reduced reads were not being handled correctly.
  • The Haplotype Score annotation no longer applies to indels.
  • Added the Variant Type annotation (not enabled by default) to annotate the VCF record with the variant type.
  • The DepthOfCoverage annotation has been renamed to Coverage.

Reduce Reads

  • Several small run time improvements were added to make this tool slightly faster.
  • By default this tool now uses a downsampling value of 40x per start position.

Indel Realigner

  • Fixed bug where some reads with soft clipped bases were not be realigned.

Combine Variants

  • Run time performance improvements added where one uses the PRIORITIZE or REQUIRE_UNIQUE options.

Select Variants

  • The --regenotype functionality has been removed from SelectVariants and transferred into its own tool: RegenotypeVariants.

Variant Eval

  • Removed the GenotypeConcordance evaluation module (which had many bugs) and converted it into its own tested, standalone tool (called GenotypeConcordance).


  • The VariantContext and related classes have been moved out of the GATK codebase and into Picard's public repository. The GATK now uses the variant.jar as an external library.
  • Added a new Read Filter to reassign just a particular mapping quality to another one (see the ReassignOneMappingQualityFilter).
  • Added the Regenotype Variants tool that allows one to regenotype a VCF file (which must contain likelihoods in the PL field) after samples have been added/removed.
  • Added the Genotype Concordance tool that calculates the concordance of one VCF file against another.
  • Bug fix for VariantsToVCF for records where old dbSNP files had '-' as the reference base.
  • The GATK now automatically converts IUPAC bases in the reference to Ns and errors out on other non-standard characters.
  • Fixed bug for the DepthOfCoverage tool which was not counting deletions correctly.
  • Added Cat Variants, a standalone tool to quickly combine multiple VCF files whose records are non-overlapping (e.g. as produced during scatter-gather).
  • The Somatic Indel Detector has been removed from our codebase and moved to the Broad Cancer group's private repository.
  • Fixed Validate Variants rsID checking which wasn't working if there were multiple IDs.
  • Picard jar updated to version 1.84.1337.
  • Tribble jar updated to version 1.84.1337.
  • Variant jar updated to version 1.85.1357.
Comments (2)

GATK release 2.2 was released on October 31, 2012. Highlights are listed below. Read the detailed version history overview here:

Base Quality Score Recalibration

  • Improved the algorithm around homopolymer runs to use a "delocalized context".
  • Massive performance improvements that allow these tools to run efficiently (and correctly) in multi-threaded mode.
  • Fixed bug where the tool failed for reads that begin with insertions.
  • Fixed bug in the scatter-gather functionality.
  • Added new argument to enable emission of the .pdf output file (see --plot_pdf_file).

Unified Genotyper

  • Massive runtime performance improvement for multi-allelic sites; -maxAltAlleles now defaults to 6.
  • The genotyper no longer emits the Stand Bias (SB) annotation by default. Use the --computeSLOD argument to enable it.
  • Added the ability to automatically down-sample out low grade contamination from the input bam files using the --contamination_fraction_to_filter argument; by default the value is set at 0.05 (5%).
  • Fixed annotations (AD, FS, DP) that were miscalculated when run on a Reduce Reads processed bam.
  • Fixed bug for the general ploidy model that occasionally caused it to choose the wrong allele when there are multiple possible alleles to choose from.
  • Fixed bug where the inbreeding coefficient was computed at monomorphic sites.
  • Fixed edge case bug where we could abort prematurely in the special case of multiple polymorphic alleles and samples with drastically different coverage.
  • Fixed bug in the general ploidy model where it wasn't counting errors in insertions correctly.
  • The FisherStrand annotation is now computed both with and without filtering low-qual bases (we compute both p-values and take the maximum one - i.e. least significant).
  • Fixed annotations (particularly AD) for indel calls; previous versions didn't accurately bin reads into the reference or alternate sets correctly.
  • Generalized ploidy model now handles reference calls correctly.

Haplotype Caller

  • Massive runtime performance improvement for multi-allelic sites; -maxAltAlleles now defaults to 6.
  • Massive runtime performance improvement to the HMM code which underlies the likelihood model of the HaplotypeCaller.
  • Added the ability to automatically down-sample out low grade contamination from the input bam files using the --contamination_fraction_to_filter argument; by default the value is set at 0.05 (5%).
  • Now requires at least 10 samples to merge variants into complex events.

Variant Annotator

  • Fixed annotations for indel calls; previous versions either didn't compute the annotations at all or did so incorrectly for many of them.

Reduce Reads

  • Fixed several bugs where certain reads were either dropped (fully or partially) or registered as occurring at the wrong genomic location.
  • Fixed bugs where in rare cases N bases were chosen as consensus over legitimate A,C,G, or T bases.
  • Significant runtime performance optimizations; the average runtime for a single exome file is now just over 2 hours.

Variant Filtration

  • Fixed a bug where DP couldn't be filtered from the FORMAT field, only from the INFO field.

Variant Eval

  • AlleleCount stratification now supports records with ploidy other than 2.

Combine Variants

  • Fixed bug where the AD field was not handled properly. We now strip the AD field out whenever the alleles change in the combined file.
  • Now outputs the first non-missing QUAL, not the maximum.

Select Variants

  • Fixed bug where the AD field was not handled properly. We now strip the AD field out whenever the alleles change in the combined file.
  • Removed the -number argument because it gave biased results.

Validate Variants

  • Added option to selectively choose particular strict validation options.
  • Fixed bug where mixed genotypes (e.g. ./1) would incorrectly fail.
  • improved the error message around unused ALT alleles.

Somatic Indel Detector

  • Fixed several bugs, including missing AD/DP header lines and putting annotations in correct order (Ref/Alt).


  • New CPU "nano" parallelization option (-nct) added GATK-wide (see docs for more details about this cool new feature that allows parallelization even for Read Walkers).
  • Fixed raw HapMap file conversion bug in VariantsToVCF.
  • Added GATK-wide command line argument (-maxRuntime) to control the maximum runtime allowed for the GATK.
  • Fixed bug in GenotypeAndValidate where it couldn't handle both SNPs and indels.
  • Fixed bug where VariantsToTable did not handle lists and nested arrays correctly.
  • Fixed bug in BCF2 writer for case where all genotypes are missing.
  • Fixed bug in DiagnoseTargets when intervals with zero coverage were present.
  • Fixed bug in Phase By Transmission when there are no likelihoods present.
  • Fixed bug in fasta .fai generation.
  • Updated and improved version of the BadCigar read filter.
  • Picard jar remains at version 1.67.1197.
  • Tribble jar remains at version 110.

 Note: There are no release notes available for versions earlier than 2.0.

These are the latest commit messages logged in the Github repository. Commit messages are short summaries that describe the changes made to the codebase. You can view the complete development history here.

Commit dateSummary
2nd October 2014 Update pom versions for the 3.3 release
2nd October 2014 Merge remote-tracking branch 'unstable/master'
2nd October 2014 Merge pull request #761 from broadinstitute/ks_junction_plugin_local_repo
2nd October 2014 Adding sysinternals:junction:1.04:exe to local repo.
2nd October 2014 Merge pull request #760 from broadinstitute/ks_queue_patches
2nd October 2014 Queue patches.
2nd October 2014 Merge pull request #759 from broadinstitute/gg_minor_docfixes
2nd October 2014 Minor documentation clarifications
2nd October 2014 Merge pull request #755 from broadinstitute/sc_Annotation_Docs_73647570
2nd October 2014 Merge pull request #740 from broadinstitute/rp_ROC_curve_total_sensitivity
2nd October 2014 Merge pull request #756 from broadinstitute/gg_fixGenotypeAndValidate
2nd October 2014 Merge pull request #757 from broadinstitute/ks_smowton_scatter_contigs_fix
2nd October 2014 Minor fixups for previous commit once tests (only runnable at Broad) were run.
2nd October 2014 Improved scatter contigs algorithm to be fairer when splitting a large number of contigs into a small number of parts.
2nd October 2014 Improvements to documentation of variant annotations
2nd October 2014 Minor fix for missing INFO key definition in VCF header
2nd October 2014 Merge pull request #743 from broadinstitute/gg_gsaweb_switchover
2nd October 2014 Merge pull request #754 from broadinstitute/rhl_variant_array_exception
2nd October 2014 Merge pull request #753 from broadinstitute/ldg_HCzeroDepth
2nd October 2014 Merge pull request #752 from broadinstitute/pd_cran_license

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For each release, we collect the Guide documentation into a Guide Book in PDF format. Each Guide Book release is versioned, so if you performed some analyses with an older version of the GATK, you can go back and look at the documentation that matched that version exactly. Note however that the Tool Documentation (GATKDocs, containing detailed argument lists) is not included in the versioned Guide Book since it can be generated directly from the source code.

 Note: There are no PDF files of the Guide Book available for versions earlier than 2.3-9.