[Leprechaunism: an inherited insulin resistance syndrome caused by the defect of insulin receptor]

Abstract

Objective: Leprechaunism is an inherited insulin resistance syndrome, caused by homozygous or compound-heterozygous mutations in the insulin receptor gene (INSR). Clinical and molecular genetic research was carried out in one 17-year old girl with leprechaunism and her family members.

Methods: History and laboratory tests were routinely taken. DNA samples were obtained from the proband and 4 of the family members. PCR was done on all exons of INSR and the products of PCR were sequenced directly.

Results: The proband had the following features: apparent cessation of growth, elfin-like face, emaciation, hirsutism and acanthosis nigricans. She had hyperglycemia (fasting blood glucose 15.8 mmol/L; glycosylated forms of hemoglobin 12%) and it was resistant to the treatment of insulin. She was found to have W659R mutation at 9 exon and V1054M mutation at 17 exon of INSR as heterozygotes. This compound mutation is a newly found type. For her father there was only V1054M mutation and her mother only W659R mutation. No mutation was identified in her sister.

Conclusion: The patient was diagnosed as leprechaunism according to her clinical presentations and biochemical examinations. The new transition mutation W659R at 9 exon and V1054M at 17 exon in INSR is the pathologic cause in this patient with leprechaunism.