Lexington High School
Lexington, MA

Katherine Chao
Medical and Population Genetics

In the past, Jiji’s relationship with science was different. “Science actually used to be my least favorite subject until we took Life Sciences in seventh grade. It sounds cheesy, but whether it was the content of the curriculum or the teacher's engaging teaching methods, I fell in love with biology that year.” From that moment forward, Jiji set out to find summer opportunities that would allow her to explore her love for science further, which led her to apply to the BSSP. “When I applied, I was willing to work in a wet lab or computational lab; I checked off all the boxes.” As part of BSSP, Jiji and her partner Chineze worked in the Translational Genomics Group (TGG). The TGG has a goal to discover the genetic basis of rare diseases. By increasing our understanding of the genetic basis underlying disease, we can shorten diagnostic odysseys and alter clinical outcomes for affected individuals. To this end, the TGG applies genomic technologies as well as novel methods to analyze data on thousands of rare disease families. There are many quality control methods that are put in place to ensure the accuracy of the genomic data being analyzed. One of these methods is accurately inferring the sex of the samples. This summer, Jiji and her partner Chineze worked on polishing sex inference code that can be used to accurately infer the sex of any given exome or genome sequencing sample. At the end of the summer, Jiji was able to optimize the code and then release it in a GitHub repository that can be accessed by anyone in the world. Additionally, as she was testing the code, she noticed there was an unexpected distribution of chromosome Y (chrY) ploidies when trying to infer the sex of the DNA samples. Instead of seeing a bimodal distribution for chrY ploidy (as expected for individuals carrying XX or XY), she saw a trimodal distribution. By plotting the distribution of chrY ploidy using different parameters, she realized a potential reason for this unexpected observation was due to differences in sequencing technologies used to obtain some of the DNA samples. When comparing samples sequenced using the same technology, she observed the expected bimodal Y distribution. Through her work, Jiji will facilitate the work of scientists around the world studying rare genetic diseases. Having a strong background as an artist, Jiji was worried about pursuing a major in science in college with little science background. However, she mentions how she can be an example to other future Broadie’s that might share a similar background as hers. “My advice to other high schoolers looking at these bios is: it is never too late—if you truly have a passion for science, BSSP will see that!”