MRC1 and Leigh syndrome: Whereas much is known about the occurrence of germline pathogenic variants in MMR genes in the setting of LS [see case 2, MLH1 (NM_000249.3); Exon 16; c.1745T>C], there is recent evidence that also other cancer susceptibility genes, many of them associated with DNA repair, harbor germline variants in individuals affected by CRCs (51, 52, 56).