Compared to those in normal colon tissues, the transcriptional levels of CLOCK, CRY1, and NR1D1 in COAD tissues were significantly higher, while the mRNA levels of ARNTL, CRY2, PER1, PER3, and RORA in COAD tissues were downregulated in the current study. The gene discussed is PER1; the disease is colon adenocarcinoma.