- A single nucleotide polymorphism in the 3'untranslated region of the CDKN2A gene is common in sporadic primary melanomas but mutations in the CDKN2B, CDKN2C, CDK4 and p53 genes are rare. Kumar, R., Smeds, J., Berggren, P., Straume, O., Rozell, B.L., Akslen, L.A., Hemminki, K. Int. J. Cancer (2001)