LS is caused by pathogenic germline variants (PGVs) in DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2) or EPCAM (leading to MSH2 silencing) and leads to earlier development of colonic adenomas, which more often have high-grade dysplasia and villous histology compared to the general population [2]. Here, PMS2 is linked to Leigh syndrome.