When examining the second most frequently reported malignancy in LS, endometrial cancer, the gene specific differences in risk are quite different with MSH2 and MSH6 being associated with an approximate 50% risk at 70 years of age whereas MLH1 risk is ~ 34% risk by 70 years of age and for PMS2 the risk is ~ 24% by 70 years of age [12, 13]. The gene discussed is MSH2; the disease is Leigh syndrome.