This showed that colorectal tumours were distinguished as a group from normal colorectal tissues by the expression of HDAC1, HDAC5, HDAC7A, SIRT1, and SUV39H1. In pairwise comparisons, all colorectal cancers showed significantly lower expression (P < 0.001) of HDAC1, HDAC5, and SIRT1,than their respective normals, except for two colorectal tumours showing higher expression of HDAC5. Higher expression of HDAC7A and SUV39H1 was observed in most colorectal tumours. This evidence concerns the gene HDAC5 and colorectal neoplasm.