Insulin resistance in an infant with leprechaunism.

A Japanese female infant with typical features of leprechaunism exhibited glucose intolerance despite marked hyperinsulinemia, indicating insulin resistance. Circulating insulin appeared to be chemically and biologically normal. There was no evidence of antagonism of insulin action or circulating antibodies to insulin or insulin receptors. Insulin receptor assay of her erythrocytes showed very low affinity despite a six-fold increase in the number of receptors as compared with those of normal adult controls. Our studies indicate that insulin resistance in this patient appears to be due to a qualitative abnormality of insulin receptors or to a postreceptor defect.