A MUT file (.mut) is a tab-delimited text file that lists mutations. The first row contains column headings and each subsequent row identifies a mutation. IGV ignores the column headings. It reads the first five columns as shown below and ignores all subsequent columns:
When a specific mutation is moused-over or clicked on, depending on user IGV display settings, a mutation information panel displays the information provided in all the columns of the MUT file, in order, for the particular mutation. For more than ~50 columns of information, only a subset of the information is displayed.