The amplification and overexpression of DPYD, a pyrimidine catabolic enzyme as the initial and rate-limiting factor in 5-FU catabolism, might contribute to poor outcomes of CRC patients receiving 5-FU-based therapy.39 In addition, the top three pathways with the most frequent copy number alternations were cell cycle (87.91%), PI3K–Akt signaling pathway (86.81%) and Ras signaling pathway (85.71%) (Figure 5). The gene discussed is DPYD; the disease is colorectal carcinoma.