All adenomas with high-grade dysplasia and all carcinomas from LS patients showed loss of MMR protein corresponding to the gene mutated in the germline whereas only 68 %, 67 % and 50 % of adenomas with low-grade dysplasia showed loss of expression in MLH1, MSH2, and MSH6 mutation carriers, respectively (Table 2). The gene discussed is MLH1; the disease is Leigh syndrome.