Deletion of exon 3 of the insulin receptor gene in a kindred with a familial form of insulin resistance

Efrat Wertheimer, Yair Litvin, Richard P. Ebstein, Estelle R. Bennet, Fabrizio Barbetti, Domenico Accili, Simeon I. Taylor

Research output: Contribution to journalArticlepeer-review

Abstract

Molecular scanning techniques, such as denaturing gradient gel electrophoresis (DGGE), greatly facilitate screening candidate genes for mutations. We have used DGGE to screen for mutations in the insulin receptor gene in a family in which four of five daughters were affected by type A insulin resistance in association with acanthosis nigricans and hyperandrogenism. DGGE did not detect mutations in any of the 22 exons of the insulin receptor gene. Nevertheless, Southern blot analysis suggested that there was a deletion of exon 3 in the other paternal allele of the insulin receptor gene. Analysis of the father's cDNA confirmed that exon 3 was deleted from mRNA molecules derived from one of his two alleles of the insulin receptor gene. Furthermore, the father was found to be hemizygous for a polymorphic sequence (GAC(Asp) at codon 234) in exon 3 that was not inherited by any of the five daughters. Instead, all five daughters inherited the paternal allele with the deletion mutation. We did not detect mutations in the mother's insulin receptor gene. Furthermore, the clinical syndrome did not segregate with either of the mother's two alleles of the insulin receptor gene. Although the youngest daughter inherited the mutant allele from her father, she was not clinically affected. The explanation for the incomplete penetrance is not known. These results emphasize the importance of specifically searching for deletion mutations when screening candidate genes for mutations. Furthermore, the existence of apparently asymptomatic carriers of mutations in the insulin receptor gene, such as the father in the present study, suggests that the prevalence of mutations in the insulin receptor gene may be higher than would be predicted on the basis of the observed prevalence of patients with extreme insulin resistance.

Original languageEnglish
Pages (from-to)1153-1158
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Volume78
Issue number5
DOIs
Publication statusPublished - May 1994

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology, Diabetes and Metabolism

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