I have been filtering and annotating vcf's generated by SomaticSniper and MuTect, and would like to run my mutation calls through MutSig to identify which genes have significant numbers of non-synonymous mutations. I think that the simplest way for me to do so is to take my data and construct a .maf, so my question is what the "minimum" number of fields with data has to be in the .maf for MutSig to run. It seems to me that all is required is mutation site, type (point vs. indel, etc), class of mutation (missense, nonsense, silent), and sample number, and that leaving other fields blank with " " placeholders should work. Are there any other fields without which MutSig cannot run?