The prevalence of multiple gene alterations (co-alterations) is higher in younger patients, with early-onset CRC showing more frequent co-occurrence of mutations such as KRAS with ATM, ARID1A, CREBBP, FAT1, KMT2B, and KMT2D, whereas these gene pairs are more often exclusive in late-onset CRC [16]. The gene discussed is ATM; the disease is colorectal carcinoma.