LS is caused by pathogenic variants in one of four DNA mismatch repair (MMR) genes (path_MMR): path_MLH1, path_MSH2, path_MSH6, and path_PMS2, each of which result in different risks for cancers, including colorectal, endometrial, ovarian, stomach, small bowel, bile duct, pancreas, urinary tract, brain, and prostate cancer.1–5 In women with LS, gynecological cancers are as common as gastrointestinal cancers. Here, MLH1 is linked to Leigh syndrome.