Identification of three novel mutations in the insulin receptor gene in type A insulin resistant patients.

Type A insulin resistance syndrome is characterized by the association of ovarian hyperandrogenism, acanthosis nigricans, and severe insulin resistance. We have identified three novel mutant alleles of the insulin receptor gene in 3 patients with type A syndrome, a severe form of insulin resistance. Two of the patients were sisters (A1, A2), 1 of them was a compound heterozygote for a mutation at the 3'-splice acceptor site of intron 21 (AG-->AA), and a missense mutation Val140Leu in exon 2. Her sister was a simple heterozygote for the 3'-splice acceptor mutation. The third patient (A3) was heterozygous for the missense mutation Ala1028Val in exon 17, in the consensus sequence for ATP binding.