MSH3 and mismatch repair cancer syndrome 1: Using the Open Custom Ranked Analysis of Variants Toolkit, we determined that this tumor had at least two variants implicated in MMR deficiency, T981M in MSH3 which is predicted to disrupt protein function according to SIFT, as well as a R248Tfs*8 in MSH6 which is predicted as pathogenic/likely pathogenic by ClinVar (61–63).