After one round of identification, two rounds of screening, and three rounds of validation, we identified a new diagnostic and prognostic biomarker for colorectal cancer at the mRNA expression level, namely ABCA5. Based on the low expression of ABCA5 in CRC and the correlation with poor prognosis, it may contribute to the diagnosis and provide new ideas for the development of molecularly targeted drugs in CRC. The gene discussed is ABCA5; the disease is colorectal carcinoma.