Genetic forms of IR include myotonic dystrophy, ataxia-telangiectasia, Alstrom syndrome, Rabson-Mendenhall syndrome, Werner syndrome, lipodystrophy, type-A IR caused by abnormalities of the insulin receptor gene, which can result in abnormal glucose homeostasis, ovarian virilization, and acanthosis nigricans, and type-B IR triggered by insulin receptor autoantibodies leading to altered glucose homeostasis, ovarian-type hyperandrogenism, and acanthosis nigricans [21]. This evidence concerns the gene INSR and acanthosis nigricans.