CDKN2A gene functions as an important tumour suppressor in various human malignancies including colorectal cancer, and its activation prevents carcinogenesis via induction of cell growth arrest and senescence. Majority of the CDKN2A mutations span exon 2 and result in loss or decreased binding to CDK4/6 leading to uncontrolled cell growth through inactivation of Rb and p53 pathways. Somatic mutations of CDKN2A are present in various tumor types but have not been well characterized in colorectal cancer. However, epigenetic silencing of CDKN2A by hypermethylation has been reported be a possible predictive factor of poor prognosis in patients with colorectal cancer.