Common variants in HNF-1 α and risk of type 2 diabetes
Journal article, 2006
Aims/hypothesis: Mutations in the hepatocyte nuclear factor 1-α gene (HNF-1α, now known as the transcription factor 1 gene [TCF1]) cause the most common monogenic form of diabetes, MODY3, but it is not known if common variants in HNF-1a are associated with decreased transcriptional activity or phenotypes related to type 2 diabetes, or whether they predict future type 2 diabetes. Subjects and methods: We studied the effect of four common polymorphisms (rs1920792, I27L, A98V and S487N) in and upstream of the HNF-1α gene on transcriptional activity in vitro, and their possible association with type 2 diabetes and insulin secretion in vivo. Results: Certain combinations of the I27L and A98V polymorphisms in the HNF-1α gene showed decreased transcriptional activity on the target promoters glucose transporter 2 (now known as solute carrier family 2 [facilitated glucose transporter], member 2) and albumin in both HeLa and INS-1 cells. In vivo, these polymorphisms were associated with a modest but significant impairment in insulin secretion in response to oral glucose. Insulin secretion deteriorated over time in individuals carrying the V allele of the A98V polymorphism (n=2,293; p=0.003). In a new case-control (n=1,511 and n=2,225 respectively) data set, the I27L polymorphism was associated with increased risk of type 2 diabetes, odds ratio (OR)=1.5 (p=0.002; multiple logistic regression), particularly in elderly (age>60 years) and overweight (BMI>25 kg/m2) patients (OR=2.3, p=0.002). Conclusions/interpretation: This study provides in vitro and in vivo evidence that common variants in the MODY3 gene, HNF-1α, influence transcriptional activity and insulin secretion in vivo. These variants are associated with a modestly increased risk of late-onset type 2 diabetes in subsets of elderly overweight individuals.