APOLIPOPROTEIN-D GENE POLYMORPHISM - A NEW GENETIC-MARKER FOR TYPE-2 DIABETIC SUBJECTS IN NAURU AND SOUTH-INDIA

Type 2 diabetes is characterized by abnormalities in both glucose and lipoprotein metabolism and genes involved in lipid metabolism are legi timate candidates for involvement in Type 2 diabetes. We have previous ly reported an association in Nauruans between a Tag 1 polymorphism of the apolipoprotein D gene (ape D) and Type 2 diabetes. In this study these findings were investigated further in the Nauruan population as well as two other ethnic groups. In South Indian subjects, there was a significant difference in genotype distribution of apo D genotypes be tween diabetic subjects (n = 110) and controls (n = 88; p = 0.004) whi ch was similar to that previously found in the Nauruan subjects. No su ch association was seen in elderly Finnish subjects (diabetic n = 69; impaired glucose tolerance n = 26 and normal glucose tolerance n = 31) . Linkage between the apo D polymorphism,and diabetes in 12 Nauruan fa milies was only excluded under a highly penetrant dominant model and w as unlikely under other single gene models. Since the p cell glucose t ransporter gene (Glut 2) is found in a similar chromosomal location to apo D, South Indian subjects (diabetic n = 95 and controls n = 56) we re typed at this locus. No association between diabetes and the Glut 2 Tag I polymorphism was found in the South Indian subjects. Furthermor e, there was no evidence of linkage disequilibrium between the apo D a nd Glut 2 genes. In conclusion, apo D might act as a modifying gene fo r Type 2 diabetes in some ethnic groups.