NTHL1 and colorectal cancer: Other genes implicated in this study included DNA base excision repair genes, MUTYH and NTHL1. Signature 36 (COSMIC v3), similar to Signature 18 detected in this study (COSMIC v2), has been associated with inactivation of MUTYH in MAP colorectal cancer [70] and observed in 5% of pancreatic neuroendocrine tumors that bore heterozygous germline MUTYH variants and subsequent loss of the wildtype allele in the tumor [71].