New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk.

Regional plots of ten novel genome-wide significant associations. For each of the ADCY5 (a), MADD (b), ADRA2A (c), FADS1 (d), CRY2 (e), SLC2A2 (f), GLIS3 (g), PROX1 (h), FAM148B (i) and IGF1 (j) regions, directly genotyped and imputed SNPs are plotted with their meta-analysis P values (as –log10 values) as a function of genomic position (NCBI Build 35). In each panel, the Stage 1 discovery SNP taken forward to Stage 2 replication is represented by a blue diamond (with global meta-analysis P value), with its Stage 1 discovery P value denoted by a red diamond. Estimated recombination rates (taken from HapMap) are plotted to reflect the local LD structure around the associated SNPs and their correlated proxies (according to a white to red scale from r2 = 0 to 1, based on pairwise r2 values from HapMap CEU). Gene annotations were taken from the University of California Santa Cruz genome browser.

Quantile-quantile (Q-Q) plots for fasting glucose (FG) (a), β-cell function by homeostasis model assessment (HOMA-B) (b), fasting insulin (FI) (c), and insulin resistance by homeostasis model assessment (HOMA-IR) (d). In each plot, the expected null distribution is plotted along the red diagonal, the entire distribution of observed P values is plotted in black, and a distribution that excludes the ten novel findings in Figure 1 is plotted in green. For FG and HOMA-B, the distribution that excludes the four genome-wide significant FG-associated loci (GCK, GCKR, G6PC2 and MTNR1B) is plotted in blue. A comparison of the observed P values for each trait shows that FG/HOMA-B associations are much more likely to be detected than FI/HOMA-IR associations.

Variation in levels of fasting glucose depending on the number of risk alleles at novel loci, weighted by effect size in an aggregate genotype score for the Framingham Heart Study. The bar plots show the average and standard error of fasting glucose in mmol/L for each value of the genotype score based on the regression coefficient (right Y axis), and the histogram denotes the number of individuals in each genotype score category (left Y axis). Comparable results were obtained for the NFBC 1966 and ARIC cohorts. On average, the range spans ~0.4 mmol/L (~7.2 mg/dl) from low to high genotype score.