The association between the loss of 5-hmC levels and malignant melanoma transformation was also supported through the study of proliferative nodules arising with congenital nevi; these nodules display some atypical features and predispose to malignant transformation, but were basically benign and exhibit—in contrast to melanomas—high 5-hmC levels and high TET2 and IDH2 activity [161]. The gene discussed is TET2; the disease is melanoma.