The instability of the CDKN2a/INK4 locus located on 9p21 is reported to be high in carcinoma and the major inactivation of the p16INK4A/p14ARF genes results from promoter methylation, homozygous deletion, loss of heterozygosity and intragenic mutation [63]. The gene discussed is CDKN2A; the disease is carcinoma.