| 1. |
- Guey, Lin T., et al.
(författare)
-
Power in the Phenotypic Extremes: A Simulation Study of Power in Discovery and Replication of Rare Variants
- 2011
-
Ingår i: Genetic Epidemiology. - : Wiley. - 0741-0395. ; 35:4, s. 236-246
-
Tidskriftsartikel (refereegranskat)abstract
- Next-generation sequencing technologies are making it possible to study the role of rare variants in human disease. Many studies balance statistical power with cost-effectiveness by (a) sampling from phenotypic extremes and (b) utilizing a two-stage design. Two-stage designs include a broad-based discovery phase and selection of a subset of potential causal genes/variants to be further examined in independent samples. We evaluate three parameters: first, the gain in statistical power due to extreme sampling to discover causal variants; second, the informativeness of initial (Phase I) association statistics to select genes/variants for follow-up; third, the impact of extreme and random sampling in (Phase 2) replication. We present a quantitative method to select individuals from the phenotypic extremes of a binary trait, and simulate disease association studies under a variety of sample sizes and sampling schemes. First, we find that while studies sampling from extremes have excellent power to discover rare variants, they have limited power to associate them to phenotype-suggesting high false-negative rates for upcoming studies. Second, consistent with previous studies, we find that the effect sizes estimated in these studies are expected to be systematically larger compared with the overall population effect size; in a well-cited lipids study, we estimate the reported effect to be twofold larger. Third, replication studies require large samples from the general population to have sufficient power; extreme sampling could reduce the required sample size as much as fourfold. Our observations offer practical guidance for the design and interpretation of studies that utilize extreme sampling. Genet. Epidemiol. 35: 236-246, 2011. (c) 2011 Wiley-Liss, Inc.
|
|
| 2. |
- Strausz, Satu, et al.
(författare)
-
Obstructive sleep apnoea and the risk for coronary heart disease and type 2 diabetes : A longitudinal population-based study in Finland
- 2018
-
Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 8:10
-
Tidskriftsartikel (refereegranskat)abstract
- Objective To evaluate if obstructive sleep apnoea (OSA) modifies the risk of coronary heart disease, type 2 diabetes (T2D) and diabetic complications in a gender-specific fashion. Design and setting A longitudinal population-based study with up to 25-year follow-up data on 36 963 individuals (>500 000 person years) from three population-based cohorts: the FINRISK study, the Health 2000 Cohort Study and the Botnia Study. Main outcome measures Incident coronary heart disease, diabetic kidney disease, T2D and all-cause mortality from the Finnish National Hospital Discharge Register and the Finnish National Causes-of-Death Register. Results After adjustments for age, sex, region, high-density lipoprotein (HDL) and total cholesterol, current cigarette smoking, body mass index, hypertension, T2D baseline and family history of stroke or myocardial infarction, OSA increased the risk for coronary heart disease (HR=1.36, p=0.0014, 95% CI 1.12 to 1.64), particularly in women (HR=2.01, 95% CI 1.31 to 3.07, p=0.0012). T2D clustered with OSA independently of obesity (HR=1.48, 95% CI 1.26 to 1.73, p=9.11× 10 7). The risk of diabetic kidney disease increased 1.75-fold in patients with OSA (95% CI 1.13 to 2.71, p=0.013). OSA increased the risk for coronary heart disease similarly among patients with T2D and in general population (HR=1.36). All-cause mortality was increased by OSA in diabetic individuals (HR=1.35, 95% CI 1.06 to 1.71, p=0.016). Conclusion OSA is an independent risk factor for coronary heart disease, T2D and diabetic kidney disease. This effect is more pronounced even in women, who until now have received less attention in diagnosis and treatment of OSA than men.
|
|
| 3. |
- Lyssenko, Valeriya, et al.
(författare)
-
Clinical risk factors, DNA variants, and the development of type 2 diabetes.
- 2008
-
Ingår i: New England Journal of Medicine. - 0028-4793. ; 359:21, s. 2220-2232
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Type 2 diabetes mellitus is thought to develop from an interaction between environmental and genetic factors. We examined whether clinical or genetic factors or both could predict progression to diabetes in two prospective cohorts. METHODS: We genotyped 16 single-nucleotide polymorphisms (SNPs) and examined clinical factors in 16,061 Swedish and 2770 Finnish subjects. Type 2 diabetes developed in 2201 (11.7%) of these subjects during a median follow-up period of 23.5 years. We also studied the effect of genetic variants on changes in insulin secretion and action over time. RESULTS: Strong predictors of diabetes were a family history of the disease, an increased body-mass index, elevated liver-enzyme levels, current smoking status, and reduced measures of insulin secretion and action. Variants in 11 genes (TCF7L2, PPARG, FTO, KCNJ11, NOTCH2, WFS1, CDKAL1, IGF2BP2, SLC30A8, JAZF1, and HHEX) were significantly associated with the risk of type 2 diabetes independently of clinical risk factors; variants in 8 of these genes were associated with impaired beta-cell function. The addition of specific genetic information to clinical factors slightly improved the prediction of future diabetes, with a slight increase in the area under the receiver-operating-characteristic curve from 0.74 to 0.75; however, the magnitude of the increase was significant (P=1.0x10(-4)). The discriminative power of genetic risk factors improved with an increasing duration of follow-up, whereas that of clinical risk factors decreased. CONCLUSIONS: As compared with clinical risk factors alone, common genetic variants associated with the risk of diabetes had a small effect on the ability to predict the future development of type 2 diabetes. The value of genetic factors increased with an increasing duration of follow-up.
|
|
| 4. |
- Saxena, Richa, et al.
(författare)
-
Genetic variation in GIPR influences the glucose and insulin responses to an oral glucose challenge
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:2, s. 142-148
-
Tidskriftsartikel (refereegranskat)abstract
- Glucose levels 2 h after an oral glucose challenge are a clinical measure of glucose tolerance used in the diagnosis of type 2 diabetes. We report a meta-analysis of nine genome-wide association studies (n = 15,234 nondiabetic individuals) and a follow-up of 29 independent loci (n = 6,958–30,620). We identify variants at the GIPR locus associated with 2-h glucose level (rs10423928, β (s.e.m.) = 0.09 (0.01) mmol/l per A allele, P = 2.0 × 10−15). The GIPR A-allele carriers also showed decreased insulin secretion (n = 22,492; insulinogenic index, P = 1.0 × 10−17; ratio of insulin to glucose area under the curve, P = 1.3 × 10−16) and diminished incretin effect (n = 804; P = 4.3 × 10−4). We also identified variants at ADCY5 (rs2877716, P = 4.2 × 10−16), VPS13C (rs17271305, P = 4.1 × 10−8), GCKR (rs1260326, P = 7.1 × 10−11) and TCF7L2 (rs7903146, P = 4.2 × 10−10) associated with 2-h glucose. Of the three newly implicated loci (GIPR, ADCY5 and VPS13C), only ADCY5 was found to be associated with type 2 diabetes in collaborating studies (n = 35,869 cases, 89,798 controls, OR = 1.12, 95% CI 1.09–1.15, P = 4.8 × 10−18).
|
|
| 5. |
- Saxena, Richa, et al.
(författare)
-
Genome-wide association analysis identifies loci for type 2 diabetes and triglyceride levels
- 2007
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 316:5829, s. 1331-1336
-
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.
|
|
| 6. |
- Voight, Benjamin F., et al.
(författare)
-
Twelve type 2 diabetes susceptibility loci identified through large-scale association analysis
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 42:7, s. 579-589
-
Tidskriftsartikel (refereegranskat)abstract
- By combining genome-wide association data from 8,130 individuals with type 2 diabetes (T2D) and 38,987 controls of European descent and following up previously unidentified meta-analysis signals in a further 34,412 cases and 59,925 controls, we identified 12 new T2D association signals with combined P < 5 x 10(-8). These include a second independent signal at the KCNQ1 locus; the first report, to our knowledge, of an X-chromosomal association (near DUSP9); and a further instance of overlap between loci implicated in monogenic and multifactorial forms of diabetes (at HNF1A). The identified loci affect both beta-cell function and insulin action, and, overall, T2D association signals show evidence of enrichment for genes involved in cell cycle regulation. We also show that a high proportion of T2D susceptibility loci harbor independent association signals influencing apparently unrelated complex traits.
|
|
| 7. |
- Yasuda, Kazuki, et al.
(författare)
-
Variants in KCNQ1 are associated with susceptibility to type 2 diabetes mellitus
- 2008
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:9, s. 1092-1097
-
Tidskriftsartikel (refereegranskat)abstract
- We carried out a multistage genome-wide association study of type 2 diabetes mellitus in Japanese individuals, with a total of 1,612 cases and 1,424 controls and 100,000 SNPs. The most significant association was obtained with SNPs in KCNQ1, and dense mapping within the gene revealed that rs2237892 in intron 15 showed the lowest P value (6.7 x 10(-13), odds ratio (OR) = 1.49). The association of KCNQ1 with type 2 diabetes was replicated in populations of Korean, Chinese and European ancestry as well as in two independent Japanese populations, and meta-analysis with a total of 19,930 individuals (9,569 cases and 10,361 controls) yielded a P value of 1.7 x 10(-42) (OR = 1.40; 95% CI = 1.34-1.47) for rs2237892. Among control subjects, the risk allele of this polymorphism was associated with impairment of insulin secretion according to the homeostasis model assessment of beta-cell function or the corrected insulin response. Our data thus implicate KCNQ1 as a diabetes susceptibility gene in groups of different ancestries.
|
|
| 8. |
- Dorkhan, Mozhgan, et al.
(författare)
-
Independent measures of insulin secretion and insulin sensitivity during the same test: the glucagon-insulin tolerance test.
- 2008
-
Ingår i: Journal of Internal Medicine. - : Wiley. - 1365-2796 .- 0954-6820. ; 264, s. 62-71
-
Tidskriftsartikel (refereegranskat)abstract
- Background. To validate a test for independent assessment of insulin secretion and insulin sensitivity during the same occasion for metabolic studies in clinical practice, i.e. combined glucagon-stimulated C-peptide test and insulin tolerance test (GITT). Subjects and methods. We measured C-peptide response to 0.5 mg of intravenous glucagon followed 30 min later by administration of 0.05 U kg(-1) insulin (insulin tolerance test, ITT). Ten subjects with normal glucose tolerance participated on different days in an ITT, glucagon-C-peptide test, ITT followed by glucagon-C-peptide test and glucagon-C-peptide test followed by ITT to establish whether and how the tests could be combined. The test was then repeated in nine patients with type 2 diabetes to investigate its reproducibility. In 20 subjects with varying degrees of glucose tolerance, the test was compared with the Botnia clamp (an intravenous glucose tolerance test combined with a euglycaemic hyperinsulinemic clamp). Results. When ITT preceded the glucagon test, C-peptide response was blunted. Therefore, we first administered glucagon and then insulin (GITT). The K(ITT) from the GITT was reproducible (CV = 13 %) and correlated strongly with the glucose disposal rate from the Botnia clamp (r = 0.87, r(2) = 0.75, P < 0.001). The C-peptide response to glucagon was reproducible (CV = 13 %). The disposition index, providing a measure of beta-cell function adjusted for insulin sensitivity, calculated from the GITT showed good discrimination between individuals with varying degrees of glucose tolerance. Conclusions. The GITT provides simple, reproducible and independent estimates of insulin sensitivity and secretion on the same occasion for metabolic studies in individuals with normal and abnormal glucose tolerance.
|
|
| 9. |
- Lethagen, ÅsaLinda, et al.
(författare)
-
Glutamic acid decarboxylase antibody positivity is associated with an impaired insulin response to glucose and arginine in nondiabetic patients with autoimmune thyroiditis
- 2002
-
Ingår i: Journal of Clinical Endocrinology and Metabolism. - 1945-7197. ; 87:3, s. 1177-1183
-
Tidskriftsartikel (refereegranskat)abstract
- To study whether antibodies to glutamic acid decarboxylase (GADab) are associated with subclinical beta-cell damage and impaired insulin secretion, we screened 441 nondiabetic patients with autoimmune thyroiditis (AT) for GADab, and 15 (3.4%) were found positive. Antibodies to IA-2 were found in two GADab+ and one GADab- patients. We matched 11 GADab+ and 13 GADab- AT patients who were euthyroid on thyroxin supplementation, and 13 control subjects for sex, age, and body mass index and measured insulin, C-peptide, and glucagon response to glucose and arginine at three blood glucose concentrations (fasting, 14 mmol/liter, >25 mmol/liter). In the fasting state, all groups had similar blood glucose concentration and HbA1c level, but the serum insulin concentration was higher in the AT patients compared with the control subjects (P < 0.04). The acute insulin response to arginine was lower in GADab+ than in GADab- thyroiditis subjects at glucose concentration of 14 and >25 mmol/liter (AIR,4: 76.8 +/- 52.0 vs. 158.2 +/- 118.2 mU/liter, P = 0.040; AIR(>25): 84.3 +/- 64.4 vs. 167.9 +/- 101.5 mU/liter, P = 0.035). In conclusion, GADab were associated with a decreased insulin secretion capacity in nondiabetic subjects with thyroiditis, which suggests that GADab positivity could be a marker of subclinical insulitis.
|
|
| 10. |
- Jujić, Amra, et al.
(författare)
-
Glucose-dependent insulinotropic peptide and risk of cardiovascular events and mortality : a prospective study
- 2020
-
Ingår i: Diabetologia. - : Springer. - 0012-186X .- 1432-0428. ; 63:5, s. 1043-1054
-
Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: Evidence that glucose-dependent insulinotropic peptide (GIP) and/or the GIP receptor (GIPR) are involved in cardiovascular biology is emerging. We hypothesised that GIP has untoward effects on cardiovascular biology, in contrast to glucagon-like peptide 1 (GLP-1), and therefore investigated the effects of GIP and GLP-1 concentrations on cardiovascular disease (CVD) and mortality risk.Methods: GIP concentrations were successfully measured during OGTTs in two independent populations (Malmo Diet Cancer-Cardiovascular Cohort [MDC-CC] and Prevalence, Prediction and Prevention of Diabetes in Botnia [PPP-Botnia]) in a total of 8044 subjects. GLP-1 (n = 3625) was measured in MDC-CC. The incidence of CVD and mortality was assessed via national/regional registers or questionnaires. Further, a two-sample Mendelian randomisation (2SMR) analysis between the GIP pathway and outcomes (coronary artery disease [CAD] and myocardial infarction) was carried out using a GIP-associated genetic variant, rs1800437, as instrumental variable. An additional reverse 2SMR was performed with CAD as exposure variable and GIP as outcome variable, with the instrumental variables constructed from 114 known genetic risk variants for CAD.Results: In meta-analyses, higher fasting levels of GIP were associated with risk of higher total mortality (HR[95% CI] = 1.22 [1.11, 1.35]; p = 4.5 x 10(-5)) and death from CVD (HR[95% CI] 1.30 [1.11, 1.52]; p = 0.001). In accordance, 2SMR analysis revealed that increasing GIP concentrations were associated with CAD and myocardial infarction, and an additional reverse 2SMR revealed no significant effect of CAD on GIP levels, thus confirming a possible effect solely of GIP on CAD.Conclusions/interpretation: In two prospective, community-based studies, elevated levels of GIP were associated with greater risk of all-cause and cardiovascular mortality within 5-9 years of follow-up, whereas GLP-1 levels were not associated with excess risk. Further studies are warranted to determine the cardiovascular effects of GIP per se.
|
|
