Variations in the vitamin D-Binding protein (Gc locus) and risk of type 2 diabetes mellitus in French Caucasians

Electrophoretic variants of the vitamin D-binding protein (DBP) have been r eported to he associated with type 2 diabetes mellitus (DM) or with prediab etic phenotypes in several non-Caucasian populations. Two frequent missense polymorphisms at codons 416 (Asp -> Glu) and 420 (Thr -> Lys) are the gene tic basis for the 3 common electrophoretic variants of DBP (Gc1F, Gc1S, and Gc2) and the resulting circulating phenotypes (Gc1F/Gc1F, Gc1F/Gc1S, Gc1S/ Gc1S, Gc1F/Gc2, Gc1S/Gc2, and Gc2/Gc2). In this study, we investigated the association of these polymorphisms with type 2 DM in French Caucasian subje cts. Variations at codons 416 and 420 were examined by polymerase chain rea ction-restriction fragment length polymorphism (PCR-RFLP). Allele frequenci es at bath codons did not differ in type 2 DM patients and in control subje cts (Asp416: 42.4% v 46.2%, respectively, P =.33; Lys420: 25.5% v 29.0%, re spectively, P =.31). Distribution of genotypes at both codons, of the haplo types defined by the 2 codons, and of the DBP phenotypes defined by the hap lotypes were also similar in diabetic and control subjects. In conclusion, our study suggests that genetic variants of the DBP gene are not associated with the susceptibility to type 2 DM in French Caucasians. Copyright (C) 2 001 by W.B. Saunders Company.