NTHL1 and colonic neoplasm: The importance of this question is underscored by observations that high-risk factors for colon cancer include biallelic mutations of 2 base excision repair genes, NTHL1 (Weren et al. 2015; Te Paske et al. 2020), and hMYH (Al-Tassan et al 2002; Wooden et al. 2004).