Rabson–Mendenhall syndrome is a rare autosomal recessive disorder characterized by severe insulin resistance. The disorder is caused by mutations in the insulin receptor gene. Symptoms include growth abnormalities of the head, face and nails, along with the development of acanthosis nigricans. Treatment involves controlling blood glucose levels by using insulin and incorporating a strategically planned, controlled diet. Also, direct actions against other symptoms may be taken (e.g. surgery for facial abnormalities) This syndrome usually affects children and has a prognosis of 1–2 years.