DNA Analysis of the Insulin-Receptor Substrate-1 Gene in a Patient with Severe Congenital Insulin Resistance
Issue: 2/1998
Author: M. Boyanov, M. Petkova*, M. Protich
Endocrinology Clinic, Medical University – Sofia *Orthodoxal Polyclinic „Sv. Luca", Diabetes Center – Sofia
Abstract:
Insulin resistance is known to be the result of genetic damage. The Insulin Receptor Substrate-1 (IRS-1) plays a major role in the insulin signal transduction.
Aim of this study was to produce clear evidence that the insulin resistance in a patient with lipoatrophic diabetes could be the result of structural changes in her IRS-1 gene.
We used cultured fibroblasts from that patient to obtain genomic DNA. Using specific polimerase-chain reaction (PCR) conditions we managed to amplify different fragments of her IRS-1 gene and further to clone them. Applying the classical as well as the direct sequencing methods we were able to sequence her IRS-1 gene in its full length.
We found 5 point mutation sites and a deletion site in her IRS-1 gene.
Under the assumption that those struc¬tural changes are not attributable to genetic polymorphism or to the cloning and sequencing reactions themselves, we suppose that they encode a different aminoacid sequence of the patient's IRS-1 protein. Although none of the since known phosphorylation sites are involved, those changes are possibly the cause of the underlying insulin resistance.
The study clearly shows that molecular medicine can in the future become a major diagnostic tool.
Keywords: Insulin-Receptor Substrate-1, IRS-1 gene, DNA analysis, mutations, insulin resistance.
