GENETIC-STUDIES OF THE SULFONYLUREA RECEPTOR GENE LOCUS IN NIDDM AND IN MORBID-OBESITY AMONG FRENCH CAUCASIANS

The sulfonylurea receptor (SUR) is a key component in glucose-stimulat ed insulin secretion. Obesity and NIDDM are frequently associated and share some metabolic abnormalities, suggesting that they might also sh are some susceptibility genes. Thus, the SUR encoding gene is a plausi ble candidate for a primary pancreatic beta-cell defect and thus for h yperglycemia and weight gain. Through association and linkage studies, we have investigated the potential role of the SUR gene in families w ith NIDDM and in two independent sets of morbidly obese families. The exon 22 T-allele at codon 761 was more common in patients with NIDDM ( 7.7%) and morbid obesity (7.8%) than in control subjects (1.8%, P = 0. 030 and P = 0.023, respectively). This variant was associated with mor bid obesity (odds ratio 3.71, P = 0.017) and NIDDM (odds ratio 2.20, P = 0.04; association dependent on BMI). Although the frequencies for i ntron 24 variant were similar in all groups, morbidly obese patients h omozygous for the c-allele had a more deleterious form of obesity. Sib -pair linkage studies with NIDDM in French Caucasian families gave no evidence for linkage to the SUR locus. However, in one set of the obes e families, we found an indication for linkage with a SUR-linked micro satellite marker (D11S419, P = 0.0032). mie conclude that in Caucasian s, the SUR locus may contribute to the genetic susceptibility NIDDM an d obesity.