Previous studies showed that MLH1 and MSH2 mutations account for 90% of LS, MSH6 mutations for 10%, and PMS2 mutations for only 5% to 6%.[5,6] These gene mutations will increase the incidence of colorectal cancer, EC, epithelial ovarian cancer, breast cancer, bladder cancer, renal cancer and gastric cancer among family members. The gene discussed is MSH2; the disease is Leigh syndrome.