| 1. |
- Ahlqvist, Emma, et al.
(författare)
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A common variant upstream of the PAX6 gene influences islet function in man.
- 2012
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 55, s. 94-104
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: Impaired glucose tolerance and impaired insulin secretion have been reported in families with PAX6 mutations and it is suggested that they result from defective proinsulin processing due to lack of prohormone convertase 1/3, encoded by PCSK1. We investigated whether a common PAX6 variant would mimic these findings and explored in detail its effect on islet function in man. METHODS: A PAX6 candidate single nucleotide polymorphism (rs685428) was associated with fasting insulin levels in the Diabetes Genetics Initiative genome-wide association study. We explored its potential association with glucose tolerance and insulin processing and secretion in three Scandinavian cohorts (N = 8,897 individuals). In addition, insulin secretion and the expression of PAX6 and transcriptional target genes were studied in human pancreatic islets. RESULTS: rs685428 G allele carriers had lower islet mRNA expression of PAX6 (p = 0.01) and PCSK1 (p = 0.001) than AA homozygotes. The G allele was associated with increased fasting insulin (p (replication) = 0.02, p (all) = 0.0008) and HOMA-insulin resistance (p (replication) = 0.02, p (all) = 0.001) as well as a lower fasting proinsulin/insulin ratio (p (all) = 0.008) and lower fasting glucagon (p = 0.04) and gastric inhibitory peptide (GIP) (p = 0.05) concentrations. Arginine-stimulated (p = 0.02) insulin secretion was reduced in vivo, which was further reflected by a reduction of glucose- and potassium-stimulated insulin secretion (p = 0.002 and p = 0.04, respectively) in human islets in vitro. CONCLUSIONS/INTERPRETATION: A common variant in PAX6 is associated with reduced PAX6 and PCSK1 expression in human islets and reduced insulin response, as well as decreased glucagon and GIP concentrations and decreased insulin sensitivity. These findings emphasise the central role of PAX6 in the regulation of islet function and glucose metabolism in man.
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| 2. |
- Alkayyali, Sami, et al.
(författare)
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Common variant in the HMGA2 gene increases susceptibility to nephropathy in patients with type 2 diabetes.
- 2012
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X.
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: Type 2 diabetes is a chronic metabolic disorder associated with devastating microvascular complications. Genome-wide association studies have identified more than 60 genetic variants associated with type 2 diabetes and/or glucose and insulin traits, but their role in the progression of diabetes is not established. The aim of this study was to explore whether these variants were also associated with the development of nephropathy in patients with type 2 diabetes. METHODS: We studied 28 genetic variants in 2,229 patients with type 2 diabetes from the local Malmö Scania Diabetes Registry (SDR) published during 2007-2010. Diabetic nephropathy (DN) was defined as micro- or macroalbuminuria and/or end-stage renal disease. Estimated glomerular filtration rate (eGFR) was assessed using the MDRD-4 formula. Replication genotyping of rs1531343 was performed in diabetic (Steno type 2 diabetes [n = 345], Genetics of Diabetes Audit and Research in Tayside Scotland [Go-DARTS] [n = 784]) and non-diabetic (Malmö Preventive Project [n = 2,523], Botnia study [n = 2,247]) cohorts. RESULTS: In the SDR, HMGA2 single-nucleotide polymorphism rs1531343 was associated with DN (OR 1.50, 95% CI 1.20, 1.87, p = 0.00035). In the combined analysis totalling 3,358 patients with type 2 diabetes (n = 1,233 cases, n = 2,125 controls), carriers of the C-allele had a 1.45-fold increased risk of developing nephropathy (95% CI 1.20, 1.75, p = 0.00010). Furthermore, the risk C-allele was associated with lower eGFR in patients with type 2 diabetes (n = 2,499, β ± SEM, -3.7 ± 1.2 ml/min, p = 0.002) and also in non-diabetic individuals (n = 17,602, β ± SEM, -0.008 ± 0.003 ml/min (log( e )), p = 0.006). CONCLUSIONS/INTERPRETATION: These data demonstrate that the HMGA2 variant seems to be associated with increased risk of developing nephropathy in patients with type 2 diabetes and lower eGFR in both diabetic and non-diabetic individuals and could thus be a common denominator in the pathogenesis of type 2 diabetes and kidney complications.
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| 3. |
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| 4. |
- Ekelund, Magnus, et al.
(författare)
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Genetic prediction of postpartum diabetes in women with gestational diabetes mellitus
- 2012
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Ingår i: Diabetes Research and Clinical Practice. - : Elsevier BV. - 1872-8227 .- 0168-8227. ; 97:3, s. 394-398
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To examine whether genetic variants that predispose individuals to type 2 diabetes (T2D) could predict the development of diabetes after gestational diabetes mellitus (GDM). Methods: 13 SNPs (FTO rs8050136, CDKAL1 rs7754840 and rs7756992, CDKN2A/2B rs10811661, HHEX rs1111875, IGF2BP2 rs1470579 and rs4402960, SLC30A8 rs13266634, TCF7L2 rs7903146, PPARG rs1801282, GCK rs1799884, HNF1A rs1169288, and KCNJ11 rs5219) were genotyped in 793 women with GDM after a median follow-up of 57 months. Results: After adjustment for age and ethnicity, the TCF7L2 rs7903146 and the FTO rs8050136 variants significantly predicted postpartum diabetes; hazard ratio (95% confidence interval 1.29 (1.01-1.66) and 1.36 (1.06-1.74), respectively (additive model) versus 1.45 (1.01-2.08) and 1.56 (1.06-2.29) (dominant model)). Adjusting for BMI attenuated the effect of the FTO variant, suggesting that the effect was mediated through its effect on BMI. Combining all risk alleles to a weighted risk score was significantly associated with the risk of postpartum diabetes (hazard ratio 1.11, 95% confidence interval 1.05-1.18, p = 0.00016 after adjustment for age and ethnicity). Conclusions: The TCF7L2 rs7903146 and FTO rs8050136 polymorphisms, and particularly a weighted risk score of T2D risk alleles, predict diabetes after GDM. Further studies in other populations are needed to confirm our results. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
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| 5. |
- Jonsson, Anna, et al.
(författare)
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Effect of a common variant of the PCSK2 gene on reduced insulin secretion.
- 2012
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X.
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Tidskriftsartikel (refereegranskat)abstract
- AIM/HYPOTHESIS: Individuals at risk of developing type 2 diabetes show a progressive decline in insulin secretion and increased insulin resistance over time. However, inability of the beta cells to compensate for the increased insulin resistance represents a key defect leading to overt type 2 diabetes. The aims of the present study were to replicate the association between genetic variants of the PCSK2 gene and insulin secretion, and to explore the effect on risk of type 2 diabetes. METHODS: Replication of PCSK2 variants against insulin secretion included 7,682 non-diabetic Scandinavian individuals. Insulin secretion was measured as the corrected insulin response or disposition index, i.e. insulin secretion adjusted for the degree of insulin resistance. Risk of type 2 diabetes was studied in 28,287 Scandinavian individuals. RESULTS: The C-allele of PCSK2 rs2208203 was associated with reduced insulin secretion measured as the corrected insulin response (n = 8,151; β = -0.112, p = 1.3 × 10(-6)) as well as disposition index (n = 8,078, β = -0.128, p = 1.6 × 10(-7)). The variant was also associated with lower fasting glucagon levels (β = -0.084, p = 0.005) in non-diabetic individuals with a fasting plasma glucose of over 5.5 mmol/l. In human pancreatic islets, PCSK2 expression correlated negatively with HbA(1c) (n = 133, r = -0.196, p = 0.038), and showed a tendency to be lower in hyperglycaemic (HbA(1c) ≥6.0% or type 2 diabetes; n = 47, p = 0.13) than normoglycaemic (HbA(1c) >6.0%; n = 66) donors. The presence of the PCSK2 rs2208203 risk allele did not influence gene expression, nor did it show an apparent risk in terms of type 2 diabetes. CONCLUSIONS/INTERPRETATION: A variant of the PCSK2 gene was associated with reduced glucose-stimulated insulin secretion, but also with lower glucagon levels, which could potentially counteract the effects of decreased insulin secretion on the risk of type 2 diabetes.
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| 6. |
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| 7. |
- Lyssenko, Valeriya, et al.
(författare)
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Validation of a multi-marker model for the prediction of incident type 2 diabetes mellitus: Combined results of the Inter99 and Botnia studies.
- 2012
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Ingår i: Diabetes & Vascular Disease Research. - : SAGE Publications. - 1752-8984 .- 1479-1641. ; 9, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To assess performance of a biomarker-based score that predicts the five-year risk of diabetes (Diabetes Risk Score, DRS) in an independent cohort that included 15-year follow-up. Method: DRS was developed on the Inter99 cohort, and validated on the Botnia cohort. Performance was benchmarked against other risk-assessment tools comparing calibration, time to event analysis, and net reclassification. Results: The area under the receiver-operating characteristic curve (AUC) was 0.84 for the Inter99 cohort and 0.78 for the Botnia cohort. In the Botnia cohort, DRS provided better discrimination than fasting plasma glucose (FPG), homeostasis model assessment of insulin resistance, oral glucose tolerance test or risk scores derived from Framingham or San Antonio Study cohorts. Overall reclassification with DRS was significantly better than using FPG and glucose tolerance status (p < 0.0001). In time to event analysis, rates of conversion to diabetes in low, moderate, and high DRS groups were significantly different (p < 0.001). Conclusion: This study validates DRS performance in an independent population, and provides a more accurate assessment of T2DM risk than other methods.
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| 8. |
- Mahdi, Taman, et al.
(författare)
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Secreted frizzled-related protein 4 reduces insulin secretion and is overexpressed in type 2 diabetes.
- 2012
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Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 16:5, s. 625-633
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Tidskriftsartikel (refereegranskat)abstract
- A plethora of candidate genes have been identified for complex polygenic disorders, but the underlying disease mechanisms remain largely unknown. We explored the pathophysiology of type 2 diabetes (T2D) by analyzing global gene expression in human pancreatic islets. A group of coexpressed genes (module), enriched for interleukin-1-related genes, was associated with T2D and reduced insulin secretion. One of the module genes that was highly overexpressed in islets from T2D patients is SFRP4, which encodes secreted frizzled-related protein 4. SFRP4 expression correlated with inflammatory markers, and its release from islets was stimulated by interleukin-1β. Elevated systemic SFRP4 caused reduced glucose tolerance through decreased islet expression of Ca(2+) channels and suppressed insulin exocytosis. SFRP4 thus provides a link between islet inflammation and impaired insulin secretion. Moreover, the protein was increased in serum from T2D patients several years before the diagnosis, suggesting that SFRP4 could be a potential biomarker for islet dysfunction in T2D.
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| 9. |
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| 10. |
- Nagorny, Cecilia, et al.
(författare)
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Tired of Diabetes Genetics? Circadian Rhythms and Diabetes: The MTNR1B Story?
- 2012
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Ingår i: Current Diabetes Reports. - : Springer Science and Business Media LLC. - 1539-0829 .- 1534-4827. ; 12:6, s. 667-672
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Tidskriftsartikel (refereegranskat)abstract
- Circadian rhythms are ubiquitous in biological systems and regulate metabolic processes throughout the body. Misalliance of these circadian rhythms and the systems they regulate has a profound impact on hormone levels and increases risk of developing metabolic diseases. Melatonin, a hormone secreted by the pineal gland, is one of the major signaling molecules used by the master circadian oscillator to entrain downstream circadian rhythms. Several recent genetic studies have pointed out that a common variant in the gene that encodes the melatonin receptor 2 (MTNR1B) is associated with impaired glucose homeostasis, reduced insulin secretion, and an increased risk of developing type 2 diabetes. Here, we try to review the role of this receptor and its signaling pathways in respect to glucose homeostasis and development of the disease.
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