Objective: The aim of our study was to determine the variant pattern of the leukemia-associated Rho guanine nucleotide exchange factor (LARG, or ARHGEF12) gene and investigate whether LARG variants are associated with diabetes mellitus type 2 (T2DM), the metabolic syndrome (MetS), or related parameters such as insulin sensitivity in German Caucasians.
Design: We analyzed single nucleotide polymorphisms (SNPs) in the LARG gene in the 55-74-year-old individuals of the population-based German Caucasian Cooperative Health Research in the region of Augsberg (KORA) survey 4 (S4).
Methods: Sequencing of Tyr1306Cys, which was of functional relevance in Pima Indians, in 48 randomly selected individuals and genotyping of 11 additional LARG SNPs in 1653 subjects were performed. Four linkage disequilibrium (LD) blocks (r(2)> or =0.8) were established and each block was statistically analyzed for association with metabolic traits. The association with T2DM and the MetS was analyzed by logistic regression in 1462 subjects, and HOMA-IR (homeostasis model assessment of insulin resistance) as a measure of insulin sensitivity was analyzed by the Kruskal-Wallis test in 1346 fasting subjects.
Results: The polymorphism Tyr1306Cys, which was significantly associated with insulin sensitivity in Pima Indians, was not found in the KORA S4 population. Statistical analysis yielded no significant associations (P>0.05) between the analyzed LARG variants and T2DM, the MetS, or related parameters such as insulin sensitivity.
Conclusions: Caucasian individuals and Pima Indians differ in their genetic variance pattern in the LARG gene region. There is no evidence in the Caucasian KORA study that variants of the LARG gene confer susceptibility for T2DM, insulin sensitivity, or the MetS.