ATM and colorectal carcinoma: This is of particular interest in CRC, in which biallelic alterations are present in only approximately 3% of cases [89], whereas monoallelic mutations in HR genes are found in as many as 86% of cases, more commonly in BRCA2, ARID1A, ataxia-telangiectasia mutated (ATM) and BRCA1 associated RING domain 1 (BARD1) [90].