[Type C insulin resistance]

Abstract

Type C insulin resistance in insulin receptor mutations is characterized by normal insulin binding to cultured fibroblasts or EB virus transformed lymphocytes from the patients and decreased insulin receptor kinase activities. However, it is sometimes difficult to classify the state of insulin resistance clearly. The intracellular beta-subunit mutations of insulin receptor which showed decreased kinase activities is reviewed here. Moreover, two cases with typical type C insulin resistance reported previously are also described. One is a case with deletion of the tyrosine kinase domain of the insulin receptor and the other is a Glycine-1008 to Valine mutation. Our studies suggest that the insulin resistance associated with these mutated genes in the kinase domain of insulin receptor were inherited, as an autosomal dominant trait.