[Physiopathological approach and antenatal diagnosis of diabetes mellitus insulin resistant: apropos of a case with leprechaunism].

BACKGROUND

Leprechaunism is characterized by severe intrauterine growth retardation, elfin-like face, relatively large hands, feet and genitalia and abnormal skin with hypertrichosis, acanthosis nigricans and low subcutaneous fat. The insulin receptors have multiple defects.

CASE REPORT

A boy was born after cesarean section at the 35th week of gestation because of intrauterine growth retardation: weight: 930 g; height: 36 cm; head circumference: 27 cm. He had trigonocephaly, coarse features and hyperkeratosis. Ultrasonography confirmed the presence of a ventricular septal defect detected during pregnancy. Hyperglucosemia (3 g/l) was associated with insulinemia above 350 mU/l; his C-peptide concentration was above 20 ng/ml. The patient was given intravenous insulin, up to 2,500 U/kg/d. He died at the age of 95 days, weighing 1500 g, with persistent hyperglucosemia and cholestasis. Postmortem examination showed adrenal and thymus hypoplasia and hyperplasia of pancreatic islet cells. Molecular biology studies showed that this patient was heterozygotic for two mutations, one in exon 20 inherited from his father, the other in exon 18 inherited from his mother; both mutations are associated with tyrosine-kinase activity of the insulin receptor. These results will be used for antenatal diagnosis in any future pregnancy.

CONCLUSION

Molecular biology can indicate specific defects in the insulin receptor. It may also allow antenatal diagnosis in some families.