EVIDENCE FOR LINKAGE OF REGIONS ON CHROMOSOME-6 AND CHROMOSOME-11 TO PLASMA-GLUCOSE CONCENTRATIONS IN MEXICAN-AMERICANS

The generic factors involved in type II diabetes are still unknown. To address this problem, we are creating a 10 to 15 cM genetic map on 44 4 individuals from 32 Mexican American families ascertained on a type II diabetic proband. Using highly polymorphic microsatellite markers a nd a multipoint variance components method, we found evidence for link age of plasma glucose concentration 2 hr after oral glucose administra tion to two regions on chromosome II: beta-hemoglobin (HBB) and marker s D11S899/D11S/324 near the sulfonylurea receptor (SUR) gene. lod scor es at these two loci were 2.77 acid 3.37, respectively. The SUR gene r egion accounted for 44.7% of the phenotypic variance. Evidence for lin kage to fasting glucose concentration was also observed for two loci o n chromosome 6, one of which is identical to a proposed susceptibility locus for type I diabetes (D6S290). When diabetics were excluded from the analyses, all lod scores became zero, suggesting that the observe d linkages were with the trait diabetes rather than with normal variat ion in glucose levels. Results were similar whether ail diabetics were included in the analyses or only those who were not under treatment w ith oral antidiabetic agents or insulin.