Some of these variants occurred in the same individual, with other alterations in different genes (in S22 and S63 concomitant with APC and TP53, and ATM alterations respectively), but other MUTYH monoallelic mutations occurred as single variants in other cases such as S39 associated with LS and S58 pertaining to an HBOC family. This evidence concerns the gene MUTYH and Leigh syndrome.