Identification of a novel insulin receptor gene heterozygous mutation in a patient with type A insulin resistance syndrome

BACKGROUND: Several types of mutations in the insulin receptor gene have been identified in patients with genetic syndromes of insulin resistance. PATIENT REPORT: We describe a 12-year-old girl with type A insulin resistance with hyperandrogenism, hyperinsulinemia, and diabetes mellitus but without the dysmorphic characteristic of leprechaunism or Rabson-Mendenhall syndrome. The proband's mother had hyperinsulinemia and diabetes mellitus but did not show any common clinical features of type A insulin resistance. The proband's brother also had hyperinsulinemia but manifested neither glucose intolerance nor common clinical features of type A insulin resistance. A novel heterozygous mutation, p.Asn1164Thr, of the insulin receptor gene (INSR) was identified in this family. CONCLUSION: These cases illustrate the diversity of clinical phenotypes associated with mutations of the insulin receptor gene.