Abstract
By using EB virus-transformed lymphocytes from two patients with insulin resistance, JRM 1 (Rabson-Mendenhall syndrome) and JA 3 (type A insulin resistance), Southern and Northern blot hybridization to human insulin receptor cDNA was performed to study possible abnormalities at the DNA and RNA levels. With the eight restriction enzymes tested, restriction fragment length polymorphisms (RFLPs) were found by Kpn I, Pee II, Rsa I and Sac I but not by Ban I, Ban II, Bgl II and Hind III. All the fragments found in these patients, however, were also observed in the normal controls suggsting that none of these RFLPs reflect any allele specific to insulin resistance and that there are no large deletions or insertions in the genomic DNA coding the insulin receptor. Northern blot analysis revealed that the molecular size and the amount of mRNA from these patients are similar to those of normal subjects. These results suggest that the causes of the decreased number of insulin receptors of these patients reside in the post-transcriptional levels.
