NTHL1 and colorectal carcinoma: In summary, the cumulative evidence, including a comprehensive genome-wide association study (GWAS) of imputed rare variants in hereditary adenomatous polyposis syndrome genes [86], suggests that monoallelic PVs in the recessively inherited genes MUTYH, NTHL1, MSH3, and MBD4 do not increase the risk of CRC or polyposis.