Leprechaunism caused by mutations in the insulin receptor gene

Leprechaunism represents the most severe form of insulin resistance syndrome, manifesting abnormal glucose metabolism and intrauterine, postnatal growth retardation. Mutations in both alleles of the insulin receptor gene have been identified. Recombinant human IGF-I treatment could prevent postnatal growth retardation and normalize glucose metabolism, however there are few reports of long-term treatment with IGF-I. We have a case of compound heterozygous mutations of the insulin receptor gene, who has been treated with IGF-I more than 11 years. Relatively higher dose of IGF-I is necessary for maintaining sufficient serum IGF-I levels. After 10 years' treatment with IGF-I, polycystic ovary, kidney enlargement, albuminuria and retinopathy are complicated in this patient. In this review, we summarized basic actions of insulin and insulin receptor, classification of mutations in the insulin receptor gene, clinical feature and our results of long-term treatment with IGF-I in leprechaunism.