Loss of CDKN2A is the most frequently observed (epi)genetic alteration in MM (observed in more than half of patients) [28]; however, alterations in cell cycle regulator genes other than CDKN2A have been described in MM: CDK4, which has also been shown to be altered in a high percentage of acral melanomas [29], and CCND1 genes were found as mutated (mostly amplified) in a not so small number of cases [15,18]. The gene discussed is CDKN2A; the disease is acral lentiginous melanoma.