PMS2 and Leigh syndrome: 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.