| 11. |
- Holmkvist, Johan, et al.
(författare)
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Common variants in HNF-1 alpha and risk of type 2 diabetes.
- 2006
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 49:Oct 11, s. 2882-2891
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Tidskriftsartikel (refereegranskat)abstract
- Mutations in the hepatocyte nuclear factor 1-alpha gene (HNF-1 alpha, 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. We studied the effect of four common polymorphisms (rs1920792, I27L, A98V and S487N) in and upstream of the HNF-1 alpha gene on transcriptional activity in vitro, and their possible association with type 2 diabetes and insulin secretion in vivo. Certain combinations of the I27L and A98V polymorphisms in the HNF-1 alpha 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 (=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/m(2)) patients (OR=2.3, p=0.002). This study provides in vitro and in vivo evidence that common variants in the MODY3 gene, HNF-1 alpha, 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.
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| 12. |
- Ling, Charlotte, et al.
(författare)
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Impact of the peroxisome proliferator activated receptor-gamma coactivator-1 beta (PGC-1 beta) Ala203Pro polymorphism on in vivo metabolism, PGC-1 beta expression and fibre type composition in human skeletal muscle
- 2007
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 50:8, s. 1615-1620
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis Peroxisome proliferator activated receptor-gamma coactivator-lp (PGC-1 beta, also known as PPARGCIB) expression is reduced in skeletal muscle from patients with type 2 diabetes mellitus and in elderly subjects. Ala203Pro, a common variant in the PGC-1 beta gene is associated with obesity. The aim of this study was to investigate whether the PGC-1 beta Ala203Pro polymorphism influences the age-related decline in skeletal muscle PGC-1 beta expression, in vivo metabolism and markers for muscle fibre type composition. Materials and methods The PGC-1 beta Ala203Pro polymerphism was genotyped in 110 young (age 28.0 +/- 1.9 years) and 86 elderly (age 62.4 +/- 2.0 years) twins and related to muscle PGC-1 beta expression, in vivo metabolism and markers for fibre type composition. Results Insulin-stimulated non-oxidative glucose metabolism (NOGM; p=0.025) and glycolytic flux rate (GF; p=0.026) were reduced in young Ala/Ala carriers compared with carriers of a 203Pro allele. In addition, a regression analysis, correcting for covariates, showed that the PGC-1 beta 203Pro allele was positively related to insulin-stimulated NOGM and GF in the young twins. While muscle expression of PGC-1 beta was reduced in elderly compared with young carriers of the Ala/Ala genotype (p <= 0.001), there was no significant age-related decline in PGC-1 beta expression in carriers of the 203Pro allele (p >= 0.4). However, a regression analysis, correcting for covariates, showed that only age was significantly related to muscle PGC-1 beta expression. Finally, PGC-1 beta expression correlated positively with markers for oxidative fibres in human muscle. Conclusions/interpretation This study suggests that young carriers of a PGC-1 beta 203Pro allele have enhanced insulin-stimulated glucose metabolism and may be protected against an age-related decline in PGC-1 beta expression in muscle.
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| 13. |
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| 14. |
- Sammalisto, S, et al.
(författare)
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A male-specific quantitative trait locus on 1p21 controlling human stature
- 2005
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Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 42:12, s. 932-939
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Tidskriftsartikel (refereegranskat)abstract
- Background: Many genome-wide scans aimed at complex traits have been statistically underpowered due to small sample size. Combining data from several genome-wide screens with comparable quantitative phenotype data should improve statistical power for the localisation of genomic regions contributing to these traits. Objective: To perform a genome-wide screen for loci affecting adult stature by combined analysis of four previously performed genome-wide scans. Methods: We developed a web based computer tool, Cartographer, for combining genetic marker maps which positions genetic markers accurately using the July 2003 release of the human genome sequence and the deCODE genetic map. Using Cartographer, we combined the primary genotype data from four genome-wide scans and performed variance components (VC) linkage analyses for human stature on the pooled dataset of 1417 individuals from 277 families and performed VC analyses for males and females separately. Results: We found significant linkage to stature on 1p21 (multipoint LOD score 4.25) and suggestive linkages on 9p24 and 18q21 (multipoint LOD scores 2.57 and 2.39, respectively) in males-only analyses. We also found suggestive linkage to 4q35 and 22q13 (multipoint LOD scores 2.18 and 2.85, respectively) when we analysed both females and males and to 13q12 (multipoint LOD score 2.66) in females-only analyses. Conclusions: We strengthened the evidence for linkage to previously reported quantitative trait loci (QTL) for stature and also found significant evidence of a novel male-specific QTL on 1p21. Further investigation of several interesting candidate genes in this region will help towards characterisation of this first sex-specific locus affecting human stature.
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| 15. |
- Saxena, Richa, et al.
(författare)
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Common single nucleotide polymorphisms in TCF7L2 are reproducibly associated with type 2 diabetes and reduce the insulin response to glucose in nondiabetic individuals
- 2006
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 55:10, s. 2890-2895
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Tidskriftsartikel (refereegranskat)abstract
- Recently, common noncoding variants in the TCF7L2 gene were strongly associated with increased risk of type 2 diabetes in samples from Iceland, Denmark, and the U.S. We genotyped 13 single nucleotide polymorphisms (SNPs) across TCF7L2 in 8,310 individuals in family-based and case-control designs from Scandinavia, Poland, and the U.S. We convincingly confirmed the previous association of TCF7L2 SNPs with the risk of type 2 diabetes (rs7903146T odds ratio 1.40 [95% CI 1.30-1.50], P = 6.74 x 10(-20)). In nondiabetic individuals, the risk genotypes were associated with a substantial reduction in the insulinogenic index derived from an oral glucose tolerance test (risk allele homozygotes have half the insulin response to glucose of noncarriers, P = 0.003) but not with increased insulin resistance. These results suggest that TCF7L2 variants may act through insulin secretion to increase the risk of type 2 diabetes.
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| 16. |
- Saxena, Richa, et al.
(författare)
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Genome-wide association analysis identifies loci for type 2 diabetes and triglyceride levels
- 2007
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 316:5829, s. 1331-1336
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Tidskriftsartikel (refereegranskat)abstract
- New strategies for prevention and treatment of type 2 diabetes (T2D) require improved insight into disease etiology. We analyzed 386,731 common single-nucleotide polymorphisms (SNPs) in 1464 patients with T2D and 1467 matched controls, each characterized for measures of glucose metabolism, lipids, obesity, and blood pressure. With collaborators (FUSION and WTCCC/UKT2D), we identified and confirmed three loci associated with T2D - in a noncoding region near CDKN2A and CDKN2B, in an intron of IGF2BP2, and an intron of CDKAL1 - and replicated associations near HHEX and in SLC30A8 found by a recent whole-genome association study. We identified and confirmed association of a SNP in an intron of glucokinase regulatory protein (GCKR) with serum triglycerides. The discovery of associated variants in unsuspected genes and outside coding regions illustrates the ability of genome-wide association studies to provide potentially important clues to the pathogenesis of common diseases.
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| 17. |
- Winckler, W, et al.
(författare)
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Association testing of variants in the hepatocyte nuclear factor 4 alpha gene with risk of type 2 diabetes in 7,883 people
- 2005
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 54:3, s. 886-892
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Tidskriftsartikel (refereegranskat)abstract
- Two recent publications reported association of common polymorphisms in the P2 promoter of hepatocyte nuclear factor 4alpha (HNF4alpha) (the MODY1 gene) with risk for type 2 diabetes. We attempted to reproduce this putative association by genotyping 11 single nucleotide polymorphism (SNPs) spanning the HNF4a coding region and the P2 promoter in >3,400 patients and control subjects from Sweden, Finland, and Canada. One SNP that was consistently associated in the two previous reports (rs1884613, in the P2 promoter region) also trended in the same direction in our sample, albeit with a lower estimated odds ratio (OR) of 1.11 (P = 0.05, one-tailed). We genotyped this SNP (rs1884613) in an additional 4,400 subjects from North America and Poland. In this sample, the association was not confirmed and trended in the opposite direction (OR 0.88). Meta-analysis of our combined sample of 7,883 people (three times larger than the two initial reports combined) yielded an OR of 0.97 (P = 0.27). Finally, we provide an updated analysis of haplotype structure in the region to guide any further investigation of common variation in HNF4alpha. Although our combined results fail to replicate the previously reported association of common variants in HNF4alpha with risk for type 2 diabetes, we cannot exclude an effect smaller than that originally proposed, heterogeneity among samples, variation in as-yet-unmeasured genotypic or environmental modifiers, or true association secondary to linkage disequilibrium (LD) with as-yet-undiscovered variant(s) in the region.
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| 18. |
- Zeggini, Eleftheria, et al.
(författare)
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Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes
- 2008
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:5, s. 638-645
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D)(1-11). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and similar to 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P=5.0 x 10(-14)), CDC123-CAMK1D (P=1.2 x 10(-10)), TSPAN8-LGR5 (P=1.1 x 10(-9)), THADA (P=1.1 x 10(-9)), ADAMTS9 (P=1.2 x 10(-8)) and NOTCH2 (P=4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D.
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