A study based on 368 carriers from 176 families with LS identified 46.8% of them with CRC (especially MLH1 carriers) and 53.2% (N = 268) with non-colonic cancers (especially MSH2, MSH6, and PMS2 carriers); three cases out of 268 with extra-colonic cancer had a TC, which at that point (in 2012), was not considered part of LS [52]. This evidence concerns the gene MSH2 and Leigh syndrome.