Genetic heterogeneity in familial hyperinsulinism

Area of Science:

• Genetics
• Endocrinology
• Molecular Biology

Background:

• Familial hyperinsulinism (HI) is a genetic disorder of insulin secretion leading to profound hypoglycemia.
• Autosomal recessive HI is linked to mutations in the Kir6.2 and sulfonylurea receptor (SUR1) genes.

Purpose of the Study:

• To investigate the spectrum and frequency of SUR1 gene mutations in familial hyperinsulinism.
• To correlate SUR1 mutations with clinical manifestations of the disease.

Main Methods:

• Screening of 45 familial hyperinsulinism probands for SUR1 mutations.
• Utilized single-strand conformation polymorphism (SSCP) and nucleotide sequence analyses of genomic DNA.

Main Results:

• Identified 17 novel and 3 previously described mutations in the SUR1 gene.
• Mutations were located in nucleotide binding domains (NBF-1, NBF-2) and transmembrane domains.
• Allelic frequencies for most mutations were rare (1.1-2.3%), except for one common mutation (4.5%).

Conclusions:

• Significant allelic heterogeneity of SUR1 mutations exists in non-Ashkenazi HI patients.
• Findings have implications for genetic counseling and prenatal diagnosis of familial hyperinsulinism.
• Provides a foundation for understanding the molecular mechanisms of HI pathophysiology.