Homozygous deletion of the human insulin receptor gene results in leprechaunism.

Homozygous inactivation of a gene, as is frequently performed to generate mouse models, provides an opportunity to elucidate the role that the gene plays in normal physiology. However, studies of human disease provide direct insight into the effect of inactivating mutations in man. In this investigation, we have identified a one year-old boy from a consanguineous pedigree who is homozygous for deletion of the insulin receptor gene resulting in leprechaunism. Contrary to previous predictions, the complete deletion of the insulin receptor gene is compatible with life.