Sex-specific effects of naturally occurring variants in the dopamine receptor D2 locus on insulin secretion and Type 2 diabetes susceptibility

Aims: Modulation of dopamine receptor D2 (DRD2) activity affects insulin secretion in both rodents and isolated pancreatic β-cells. We hypothesized that single nucleotide polymorphisms in the DRD2/ANKK1 locus may affect susceptibility to Type 2 diabetes in humans. Methods: Four potentially functional variants in the coding region of the DRD2/ANKK1 locus (rs1079597, rs6275, rs6277, rs1800497) were genotyped and analysed for Type 2 diabetes susceptibility in up to 25 000 people (8148 with Type 2 diabetes and 17687 control subjects) from two large independent Dutch cohorts and one Danish cohort. In addition, 340 Dutch subjects underwent a 2-h hyperglycaemic clamp to investigate insulin secretion. Since sexual dimorphic associations related to DRD2 polymorphisms have been previously reported, we also performed a gender-stratified analysis. Results: rs1800497 at the DRD2/ANKK1 locus was associated with a significantly increased risk for Type 2 diabetes in women (odds ratio 1.14 (1.06-1.23); P = 4.1*10-4) but not in men (odds ratio 1.00 (95% CI 0.93-1.07); P = 0.92) or the combined group. Although rs1800497 was not associated with insulin secretion, we did find another single nucleotide polymorphism in this locus, rs6275, to be associated with increased first-phase glucose-stimulated insulin secretion in women (P = 5.5*10-4) but again not in men (P = 0.34). Conclusion: The present data identify DRD2/ANKK1 as a potential sex-specific Type 2 diabetes susceptibility gene. What's new?: The rs1800497 single nucleotide polymorphism at the DRD2/ANKK1 locus was associated with a significantly increased risk for Type 2 diabetes in women but not in men. The rs6275 single nucleotide polymorphism in the DRD2 gene is associated with increased first-phase glucose-stimulated insulin secretion in women only. Our data identify DRD2/ANKK1 as a potential sex-specific Type 2 diabetes susceptibility gene.

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