NTHL1 and colorectal carcinoma: DNAs from the 94 familial CRC without germline mutations in the known CRC predisposition loci were screened for sequence variants in NTHL1, NEIL1, NEIL2, MPG, TDG, UNG and SMUG1. The average age at diagnosis of CRC in the cases was 54.8 years (SD, 9.3 years; median age 56 years).