ATM and colorectal carcinoma: In a 2021 Spanish Ministry-funded study that examined both familial and sporadic early-onset CRC, approximately 13% of patients with early-onset CRC were found to carry pathogenic germline variants in known cancer predisposition genes, and around 2.5% of cases harbor genes that are not associated with colorectal cancer, such as BRCA1, BRCA2, TP53, ATM, CHEK2, PALB2, and CDKN2A [26].