title: Variants at DGKB/TMEM195, ADRA2A, GLIS3 and C2CD4B loci are associated with reduced glucose-stimulated beta cell function in middle-aged Danish people.
abstract: OBJECTIVE
  A meta-analysis of 21 genome-wide association studies identified 11 novel genetic loci implicated in fasting glucose homeostasis. We aimed to evaluate the impact of these variants on insulin release and insulin sensitivity estimated from OGTTs.
  
  
  METHODS
  Eleven variants in or near DGKB/TMEM195, ADCY5, MADD, ADRA2A, FADS1, CRY2, SLC2A2, GLIS3, PROX1, C2CD4B and IGF1 were genotyped in 6,784 middle-aged participants of the population-based Inter99 cohort. Association studies of quantitative estimates of insulin release and insulin sensitivity were performed in 5,722 non-diabetic Danish participants on whom an OGTT was performed.
  
  
  RESULTS
  Assuming an additive genetic model, carriers of the alleles increasing fasting glucose in DGKB/TMEM195, ADRA2A, GLIS3 and C2CD4B showed decreased glucose-stimulated insulin release as assessed by the BIGTT-acute insulin response index (2.7-3.5%; p < 0.005 for all) and by corrected insulin response (2.8-5.9%; p < 0.03 for all). In addition, the PROX1 glucose-raising allele showed a 2.9% decreased corrected insulin response (p = 0.03), while the hyperglycaemic allele of variants in or near ADRA2A, FADS1, CRY2 and C2CD4B were associated with a 2.6% to 9.3% decrease in one or both of two different OGTT-based disposition indices (p < 0.02 for all). After correction for multiple testing, variants in the DGKB/TMEM195, ADRA2A, GLIS3 and C2CD4B loci were associated with estimates of beta cell function.
  
  
  CONCLUSIONS
  We found that the lead variants at the DGKB/TMEM195, ADRA2A, GLIS3 and C2CD4B loci were associated with decreased glucose-stimulated insulin response. This association underlines the importance of pancreatic beta cell dysfunction in the genetic predisposition to hyperglycaemia and type 2 diabetes.
authors.affiliation: Hagedorn Research Institute, Niels Steensens Vej 2, 2820 Gentofte, Denmark.
authors.forename: T W
authors.initials: TW
authors.lastname: Boesgaard
authors.forename: N
authors.initials: N
authors.lastname: Grarup
authors.forename: T
authors.initials: T
authors.lastname: Jørgensen
authors.forename: K
authors.initials: K
authors.lastname: Borch-Johnsen
authors.forename: T
authors.initials: T
authors.lastname: Hansen
authors.forename: O
authors.initials: O
authors.lastname: Pedersen
mesh_terms: D004268:DNA-Binding Proteins; D000090943:Delta-5 Fatty Acid Desaturase; D003718:Denmark; D019852:Diacylglycerol Kinase / Q000235:genetics*; D005260:Female; D056426:Genetic Loci; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D005838:Genotype; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D050417:Insulin-Secreting Cells / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins; D018341:Receptors, Adrenergic, alpha-2 / Q000235:genetics*; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*
chemical_list: C547768:ADRA2A protein, human; C494528:C2CD4B protein, human; D004268:DNA-Binding Proteins; D000090943:Delta-5 Fatty Acid Desaturase; C512851:GLIS3 protein, human; D009687:Nuclear Proteins; D018341:Receptors, Adrenergic, alpha-2; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C000716847:FADS1 protein, human; D019852:Diacylglycerol Kinase; D005947:Glucose