The pathogenicity of somatic MYH mutations is thought to primarily arise from the accumulation of G:C → T:A transversions in APC, which results in carriers of monoallelic disease-causing MUTYH strain variants having a higher risk of developing tumors.138 A diverse array of somatic MYH mutations, including both nonsense and missense variants, have been identified in CRC patients.139 It is noteworthy that some patients exhibit only a single detectable somatic MYH mutation, suggesting the presence of other elusive mutations.140 When both alleles of MYH are mutated, the penetrance is very high. This evidence concerns the gene APC and colorectal carcinoma.