title: Novel meta-analysis-derived type 2 diabetes risk loci do not determine prediabetic phenotypes.
abstract: BACKGROUND
  Genome-wide association (GWA) studies identified a series of novel type 2 diabetes risk loci. Most of them were subsequently demonstrated to affect insulin secretion of pancreatic beta-cells. Very recently, a meta-analysis of GWA data revealed nine additional risk loci with still undefined roles in the pathogenesis of type 2 diabetes. Using our thoroughly phenotyped cohort of subjects at an increased risk for type 2 diabetes, we assessed the association of the nine latest genetic variants with the predominant prediabetes traits, i.e., obesity, impaired insulin secretion, and insulin resistance.
  
  
  RESULTS
  One thousand five hundred and seventy-eight metabolically characterized non-diabetic German subjects were genotyped for the reported candidate single nucleotide polymorphisms (SNPs) JAZF1 rs864745, CDC123/CAMK1D rs12779790, TSPAN8/LGR5 rs7961581, THADA rs7578597, ADAMTS9 rs4607103, NOTCH2 rs10923931, DCD rs1153188, VEGFA rs9472138, and BCL11A rs10490072. Insulin sensitivity was derived from fasting glucose and insulin concentrations, oral glucose tolerance test (OGTT), and hyperinsulinemic-euglycemic clamp. Insulin secretion was estimated from OGTT data. After appropriate adjustment for confounding variables and Bonferroni correction for multiple comparisons (corrected alpha-level: p = 0.0014), none of the SNPs was reliably associated with adiposity, insulin sensitivity, or insulin secretion (all p > or = 0.0117, dominant inheritance model). The risk alleles of ADAMTS9 SNP rs4607103 and VEGFA SNP rs9472138 tended to associate with more than one measure of insulin sensitivity and insulin secretion, respectively, but did not reach formal statistical significance. The study was sufficiently powered (1-beta = 0.8) to detect effect sizes of 0.19 < or = d < or = 0.25 (alpha = 0.0014) and 0.13 < or = d < or = 0.16 (alpha = 0.05).
  
  
  CONCLUSIONS
  In contrast to the first series of GWA-derived type 2 diabetes candidate SNPs, we could not detect reliable associations of the novel risk loci with prediabetic phenotypes. Possible weak effects of ADAMTS9 SNP rs4607103 and VEGFA SNP rs9472138 on insulin sensitivity and insulin secretion, respectively, await further confirmation by larger studies.
authors: Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology, and Clinical Chemistry, University Hospital Tübingen, Tübingen, Germany. harald.staiger@med.uni-tuebingen.de
authors: Harald
authors: H
authors: Staiger
authors: Fausto
authors: F
authors: Machicao
authors: Konstantinos
authors: K
authors: Kantartzis
authors: Silke A
authors: SA
authors: Schäfer
authors: Kerstin
authors: K
authors: Kirchhoff
authors: Martina
authors: M
authors: Guthoff
authors: Günther
authors: G
authors: Silbernagel
authors: Norbert
authors: N
authors: Stefan
authors: Andreas
authors: A
authors: Fritsche
authors: Hans-Ulrich
authors: HU
authors: Häring
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D049628:Body Size; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology / Q000235:genetics*; D017097:Electric Impedance; D005260:Female; D015894:Genome, Human; D005838:Genotype; D005858:Germany; D005951:Glucose Tolerance Test; D006801:Humans; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011236:Prediabetic State / Q000235:genetics*; D012016:Reference Values; D015203:Reproducibility of Results; D018570:Risk Assessment; D044465:White People / Q000235:genetics