This study was undertaken to identify genetic polymorphisms that are associated with the risk of an elevated fasting glucose (FG) level using genome-wide analyses. We explored a quantitative trait locus (QTL) for FG level in a genome-wide study from a Korean twin-family cohort (the Healthy Twin Study) using a combined linkage and family-based association analysis approach. We investigated 1,754 individuals, which included 432 families and 219 pairs of monozygotic twins. Regions of chromosomes 2q23.3-2q31.1, 15q26.1-15q26.3, 16p12.1, and 20p13-20p12.2, were found to show evidence of linkage with FG level, and several markers in these regions were found to be significantly associated with FG level using family-based or general association tests. In particular, a single-nucleotide polymorphism (rs6138953) on the PTPRA gene in the 20p13 region (combined P = 1.8 x 10(-6)) was found to be associated with FG level, and the PRKCB1 gene (in 16p12.1) to be possibly associated with FG level. In conclusion, multiple regions of chromosomes 2q23.3-2q31.1, 15q26.1-15q26.3, 16p12.1, and 20p13-20p12.2 are associated with FG level in our Korean twin-family cohort. The combined approach of genome-wide linkage and family-based association analysis is useful to identify novel or known genetic regions concerning FG level in a family cohort study.
Adult ; Aged ; Asian Continental Ancestry Group/*genetics ; Blood Glucose/*genetics ; Chromosomes, Human, Pair 15/genetics ; Chromosomes, Human, Pair 16/genetics ; Chromosomes, Human, Pair 2/genetics ; Chromosomes, Human, Pair 20/genetics ; Cohort Studies ; Family ; Female ; *Genetic Linkage ; *Genome-Wide Association Study ; Genotype ; Humans ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; Protein Kinase C/genetics ; Quantitative Trait Loci ; Receptor-Like Protein Tyrosine Phosphatases, Class 4/*genetics ; Republic of Korea ; Twins, Monozygotic/*genetics