Phenotypic and genotypic differences between Indian and Scandinavian women with gestational diabetes mellitus.

OBJECTIVE: Gestational diabetes mellitus (GDM) is a transient form of diabetes characterized by impaired insulin secretion and action during pregnancy. Population-based differences in prevalence exist which could be explained by phenotypic and genetic differences. The aim of this study was to examine these differences in pregnant women from Punjab, India and Scandinavia. METHODS: Eighty-five GDM/T2D loci in European and/or Indian populations from previous studies were assessed for association with GDM based on Swedish GDM criteria in 4018 Punjabi Indian and 507 Swedish pregnant women. Selected loci were replicated in Scandinavian cohorts, Radiel (N = 398, Finnish) and STORK/STORK-G (N = 780, Norwegian). RESULTS: Punjabi Indian women had higher GDM prevalence, lower insulin secretion and better insulin sensitivity than Swedish women. There were significant frequency differences of GDM/T2D risk alleles between both populations. rs7178572 at HMG20A, previously associated with GDM in South Indian and European women, was replicated in North Indian women. The T2D risk SNP rs11605924 in the CRY2 gene was associated with increased GDM risk in Scandinavian but decreased GDM risk in Punjabi Indian women. No other overlap was seen between GDM loci in both populations. CONCLUSIONS: Gestational diabetes mellitus is more common in Indian than Swedish women, which partially can be attributed to differences in insulin secretion and action. There was marked heterogeneity in the GDM phenotypes between the populations which could only partially be explained by genetic differences.

A genetic risk score for hypertension is associated with risk of thoracic aortic aneurysm.

A genetic risk score (GRS) based on 29 single nucleotide polymorpysms (SNPs) associated with high blood pressure (BP) was prospectively associated with development of hypertension, stroke and cardiovascular events. The aim of the present study was to evaluate the impact of this GRS on the incidence of aortic disease, including aortic dissection (AD), rupture or surgery of a thoracic (TAA) or abdominal (AAA) aortic aneurysm. More than 25,000 people from the Swedish Malmo Diet and Cancer Study had information on at least 24 SNPs and were followed up for a median ≥ 18 years. The number of BP elevating alleles of each SNPs, weighted by their effect size in the discovery studies, was summed into a BP-GRS. In Cox regression models, adjusted for traditional cardiovascular risk factors including hypertension, we found significant associations of the BP-GRS, prospectively, with incident TAA (hazard ratio (HR) 1.64 (95% confidence interval (CI) 1.081-2.475 comparing the third vs. the first tertile; p = 0.020) but not with either AAA or aortic dissection. Calibration, discrimination and reclassification analyses show modest improvement in prediction using the BP-GRS in addition to the model which used only traditional risk factors. A GRS for hypertension associates with TAA suggesting a link between genetic determinants of BP and aortic disease. The effect size is small but the addition of more SNPs to the GRS might improve its discriminatory capability.

Plasma levels of the proprotein convertase furin and incidence of diabetes and mortality.

BACKGROUND: Diabetes mellitus is linked to premature mortality of virtually all causes. Furin is a proprotein convertase broadly involved in the maintenance of cellular homeostasis; however, little is known about its role in the development of diabetes mellitus and risk of premature mortality. OBJECTIVES: To test if fasting plasma concentration of furin is associated with the development of diabetes mellitus and mortality. METHODS: Overnight fasted plasma furin levels were measured at baseline examination in 4678 individuals from the population-based prospective Malmö Diet and Cancer Study. We studied the relation of plasma furin levels with metabolic and hemodynamic traits. We used multivariable Cox proportional hazards models to investigate the association between baseline plasma furin levels and incidence of diabetes mellitus and mortality during 21.3-21.7 years follow-up. RESULTS: An association was observed between quartiles of furin concentration at baseline and body mass index, blood pressure and plasma concentration of glucose, insulin, LDL and HDL cholesterol (|0.11| ≤ ß ≤ |0.31|, P < 0.001). Plasma furin (hazard ratio [HR] per one standard deviation increment of furin) was predictive of future diabetes mellitus (727 events; HR = 1.24, CI = 1.14-1.36, P < 0.001) after adjustment for age, sex, body mass index, systolic and diastolic blood pressure, use of antihypertensive treatment, alcohol intake and fasting plasma level of glucose, insulin and lipoproteins cholesterol. Furin was also independently related to the risk of all-cause mortality (1229 events; HR = 1.12, CI = 1.05-1.19, P = 0.001) after full multivariable adjustment. CONCLUSION: Individuals with high plasma furin concentration have a pronounced dysmetabolic phenotype and elevated risk of diabetes mellitus and premature mortality.

Plasma stem cell factor levels are associated with risk of cardiovascular disease and death.

OBJECTIVE: Stem cell factor (SCF) is a key growth factor for several types of stem and progenitor cells. There is experimental evidence that such cells are of importance for maintaining the integrity of the cardiovascular system. We investigated the association between circulating levels of SCF and risk for development of cardiovascular events and death. METHODS: SCF was analysed by the proximity extension assay technique in plasma from 4742 subjects participating in the Malmö Diet and Cancer Study. Cardiovascular events and death were monitored through national registers with a mean follow-up time of 19.2 years. RESULTS: Subjects with high baseline levels of SCF had lower cardiovascular (n = 340) and all-cause mortality (n = 1159) as well as a lower risk of heart failure (n = 177), stroke (n = 318) and myocardial infarction (n = 452). Smoking, diabetes and high alcohol consumption were associated with lower levels of SCF. Single nucleotide polymorphisms in the gene region encoding PDX1 C-terminal inhibiting factor 1 (PCIF1) and matrix metalloproteinase-9 were associated with plasma SCF levels. The highest SCF quartile remained independently associated with a lower risk of a lower risk of cardiovascular [hazard ratio and 95% confidence interval 0.59 (0.43-0.81)] and all-cause mortality [0.68 (0.57-0.81)], heart failure [0.50 (0.31-0.80)] and stroke [0.66 (0.47-0.92)], but not with MI [0.96 (0.72-1.27)] as compared with the lowest quartile when adjusting for traditional cardiovascular risk factors in Cox proportional hazard regression models. CONCLUSIONS: This prospective population-based study demonstrates that subjects with high levels of SCF have a lower risk of cardiovascular events and death. The findings provide clinical support for a protective role of SCF in maintaining cardiovascular integrity.

Insulin secretion and action in North Indian women during pregnancy.

AIM: The relative roles(s) of impaired insulin secretion vs. insulin resistance in the development of gestational diabetes mellitus depend upon multiple risk factors and diagnostic criteria. Here, we explored their relative contribution to gestational diabetes as defined by the WHO 1999 (GDM1999) and adapted WHO 2013 (GDM2013) criteria, excluding the 1-h glucose value, in a high-risk Indian population from Punjab. METHODS: Insulin secretion (HOMA2-B) and insulin action (HOMA2-IR) were assessed in 4665 Indian women with or without gestational diabetes defined by the GDM1999 or adapted GDM2013 criteria. RESULTS: Gestational diabetes defined using both criteria was associated with decreased insulin secretion compared with pregnant women with normal glucose tolerance. Women with gestational diabetes defined by the adapted GDM2013, but not GDM1999 criteria, were more insulin resistant than pregnant women with normal glucose tolerance, and furthermore displayed lower insulin secretion than GDM1999 women. Urban habitat, illiteracy, high age and low BMI were independently associated with reduced insulin secretion, whereas Sikh religion, increasing age and BMI, as well as a family history of diabetes were independently associated with increased insulin resistance. CONCLUSIONS: Gestational diabetes risk factors influence insulin secretion and action in North Indian women in a differential manner. Gestational diabetes classified using the adapted GDM2013 compared with GDM1999 criteria is associated with more severe impairments of insulin secretion and action.

Exome array analysis of ischaemic stroke: results from a southern Swedish study.

BACKGROUND AND PURPOSE: Genome-wide association (GWA) studies have identified a few risk loci for ischaemic stroke, but these variants explain only a small part of the genetic contribution to the disease. Coding variants associated with amino acid substitutions or premature termination of protein synthesis could have a large effect on disease risk. We performed an exome array analysis for ischaemic stroke. METHODS: Patients with ischaemic stroke (n = 2385) and control subjects (n = 6077) from three Swedish studies were genotyped with the Illumina HumanOmniExpressExome BeadChip. Single-variant association analysis and gene-based tests were performed of exome variants with minor allele frequency of < 5%. A separate GWA analysis was also performed, based on 700 000 genotyped common markers and subsequent imputation. RESULTS: No exome variant or gene was significantly associated with all ischaemic stroke after Bonferroni correction (all P > 1.8 × 10-6 for single-variant and >4.15 × 10-6 for gene-based analysis). The strongest association in single-variant analysis was found for a missense variant in the DNAH11 gene (rs143362381; P = 5.01 × 10-6 ). In gene-based tests, the strongest association was for the ZBTB20 gene (P = 7.9 × 10-5 ). The GWA analysis showed that the sample was homogenous (median genomic inflation factor = 1.006). No genome-wide significant association with overall ischaemic stroke risk was found. However, previously reported associations for the PITX2 and ZFHX3 gene loci with cardioembolic stroke subtype were replicated (P = 7 × 10-15 and 6 × 10-3 ). CONCLUSIONS: This exome array analysis did not identify any single variants or genes reaching the pre-defined significance level for association with ischaemic stroke. Further studies on exome variants should be performed in even larger, well-defined and subtyped samples.

Inverse relationship between a genetic risk score of 31 BMI loci and weight change before and after reaching middle age.

BACKGROUND/OBJECTIVE: Genome-wide-association studies have identified numerous body mass index (BMI)-associated variants, but it is unclear how these relate to weight gain in adults at different ages. METHODS: We examined the association of a genetic risk score (GRS), consisting of 31 BMI-associated variants, with an annual weight change (AWC) and a substantial weight gain (SWG) of 10% by comparing self-reported weight at 20 years (y) with baseline weight (mean: 58 y; s.d.: 8 y) in 21407 participants from the Malmö Diet and Cancer Study (MDCS), and comparing baseline weight to weight at follow-up (mean: 73 y; s.d.: 6 y) among 2673 participants. Association between GRS and AWG and SWG was replicated in 4327 GLACIER (Gene x Lifestyle interactions And Complex traits Involved in Elevated disease Risk) participants (mean: 45 y; s.d.: 7 y) with 10 y follow-up. Cohort-specific results were pooled by fixed-effect meta-analyses. RESULTS: In MDCS, the GRS was associated with increased AWC (ß: 0.003; s.e: 0.01; P: 7 × 10(-8)) and increased odds for SWG (odds ratio (OR) 1.01 (95% confidence interval (CI): 1.00, 1.02); P: 0.013) per risk-allele from age 20y, but unexpectedly with decreased AWC (ß: -0.006; s.e: 0.002; P: 0.009) and decreased odds for SWG OR 0.96 (95% CI: 0.93, 0.98); P: 0.001) between baseline and follow-up. Effect estimates from age 20 y to baseline differed significantly from those from baseline to follow-up (P: 0.0002 for AWC and P: 0.0001 for SWG). Similar to MDCS, the GRS was associated with decreased odds for SWG OR 0.98 (95% CI: 0.96, 1.00); P: 0.029) from baseline to follow-up in GLACIER. In meta-analyses (n=7000), the GRS was associated with decreased AWC (ß: -0.005; s.e.m. 0.002; P: 0.002) and decreased odds for SWG OR 0.97 (95% CI: 0.96, 0.99); P: 0.001) per risk-allele. CONCLUSIONS: Our results provide convincing evidence for a paradoxical inversed relationship between a high number of BMI-associated risk-alleles and less weight gain during and after middle-age, in contrast to the expected increased weight gain seen in younger age.

Less pronounced response to exercise in healthy relatives to type 2 diabetic subjects compared with controls.

Healthy first-degree relatives with heredity of type 2 diabetes (FH+) are known to have metabolic inflexibility compared with subjects without heredity for diabetes (FH-). In this study, we aimed to test the hypothesis that FH+ individuals have an impaired response to exercise compared with FH-. Sixteen FH+ and 19 FH- insulin-sensitive men similar in age, peak oxygen consumption (V̇o2 peak), and body mass index completed an exercise intervention with heart rate monitored during exercise for 7 mo. Before and after the exercise intervention, the participants underwent a physical examination and tests for glucose tolerance and exercise capacity, and muscle biopsies were taken for expression analysis. The participants attended, on average, 39 training sessions during the intervention and spent 18.8 MJ on exercise. V̇o2 peak/kg increased by 14%, and the participants lost 1.2 kg of weight and 3 cm waist circumference. Given that the FH+ group expended 61% more energy during the intervention, we used regression analysis to analyze the response in the FH+ and FH- groups separately. Exercise volume had a significant effect on V̇o2 peak, weight, and waist circumference in the FH- group, but not in the FH+ group. After exercise, expression of genes involved in metabolism, oxidative phosphorylation, and cellular respiration increased more in the FH- compared with the FH+ group. This suggests that healthy, insulin-sensitive FH+ and FH- participants with similar age, V̇o2 peak, and body mass index may respond differently to an exercise intervention. The FH+ background might limit muscle adaptation to exercise, which may contribute to the increased susceptibility to type 2 diabetes in FH+ individuals.

Cystatin C identifies cardiovascular risk better than creatinine-based estimates of glomerular filtration in middle-aged individuals without a history of cardiovascular disease.

OBJECTIVES: Creatinine- and cystatin C-based estimates of renal function are considered to be cardiovascular disease (CVD) risk factors, but the clinical utility in middle-aged subjects without a history of CVD is controversial. DESIGN: We related plasma cystatin C and creatinine-based glomerular filtration rate (GFR) [MDRD, CKD-EPI-2009, and CKD-EPI-comb (a combination of creatinine and cystatin C)] to incident CVD, CVD mortality, all-cause mortality, and heart failure in 4650 middle-aged subjects without CVD. RESULTS: The hazard ratio (HR) per standard deviation increment (95% CI) of cystatin C predicted incident CVD (1.22, 1.11-1.33; P < 0.0001), CVD mortality (1.44, 1.24-1.66; P < 0.0001), all-cause mortality (1.15, 1.05-1.26; P = 0.002), and heart failure (1.27, 1.05-1.55; P = 0.02), whereas MDRD and CKD-EPI-2009 only predicted CVD mortality (0.79, 0.66-0.93; P = 0.006 and 0.78, 0.66-0.92; P = 0.003, respectively). Cystatin C led to a significant increase in the net reclassification improvement for all endpoints, except heart failure. Only within the quartile with the worst renal function were all measures related to all-cause and CVD mortality. The top 25% of cystatin C in the population significantly predicted risk of incident CVD and CVD mortality, whereas MDRD and CKD-EPI-2009 were predictors of CVD mortality only at a GFR < 60 mL/min/1.73 m(2) (11-13% of the population) and of incident CVD only at a GFR < 45 mL/min/1.73 m(2) (<1% of the population). CONCLUSION: Cystatin C is a better risk marker for CVD morbidity and mortality than creatinine-based GFR. Whether this is explained by cystatin C being a better marker for true GFR or through other effects of cystatin C remains to be shown.

Chromosome 9p21 genetic variation explains 13% of cardiovascular disease incidence but does not improve risk prediction.

OBJECTIVES: To evaluate the proportion of cardiovascular disease (CVD) incidence that is explained by genetic variation at chromosome 9p21 and to test whether such variation adds incremental information with regard to CVD prediction, beyond traditional risk factors. DESIGN, SETTING AND PARTICIPANTS: rs4977574 on chromosome 9p21 was genotyped in 24 777 subjects from the Malmö Diet and Cancer study who were free from CVD prior to the baseline examination. Association between genotype and incident CVD (n = 2668) during a median follow-up of 11.7 years was evaluated in multivariate Cox proportional hazard models. Analyses were performed in quartiles of baseline age, and linear trends in effect size across age groups were estimated in logistic regression models. RESULTS: In additive models, chromosome 9p21 significantly predicted CVD in the entire population (hazard ratio 1.17 per G allele, 95% confidence interval 1.11-1.23, P < 0.001). Effect estimates increased from the highest (Q4) to the lowest quartile (Q1) of baseline age, but this trend was not significant. The overall population attributable risk conferred by chromosome 9p21 in fully adjusted models was 13%, ranging from 17% in Q1 to 11% in Q4. Addition of chromosome 9p21 to traditional risk factors only marginally improved predictive accuracy. CONCLUSION: The high population attributable risk conferred by chromosome 9p21 suggests that future interventions interfering with downstream mechanisms of the genetic variation may affect CVD incidence over a broad range of ages. However, variation of chromosome 9p21 alone does not add clinically meaningful information in terms of CVD prediction beyond traditional risk factors at any age.

Identification of CpG-SNPs associated with type 2 diabetes and differential DNA methylation in human pancreatic islets.

AIMS/HYPOTHESIS: To date, the molecular function of most of the reported type 2 diabetes-associated loci remains unknown. The introduction or removal of cytosine-phosphate-guanine (CpG) dinucleotides, which are possible sites of DNA methylation, has been suggested as a potential mechanism through which single-nucleotide polymorphisms (SNPs) can affect gene function via epigenetics. The aim of this study was to examine if any of 40 SNPs previously associated with type 2 diabetes introduce or remove a CpG site and if these CpG-SNPs are associated with differential DNA methylation in pancreatic islets of 84 human donors. METHODS: DNA methylation was analysed using pyrosequencing. RESULTS: We found that 19 of 40 (48%) type 2 diabetes-associated SNPs introduce or remove a CpG site. Successful DNA methylation data were generated for 16 of these 19 CpG-SNP loci, representing the candidate genes TCF7L2, KCNQ1, PPARG, HHEX, CDKN2A, SLC30A8, DUSP9, CDKAL1, ADCY5, SRR, WFS1, IRS1, DUSP8, HMGA2, TSPAN8 and CHCHD9. All analysed CpG-SNPs were associated with differential DNA methylation of the CpG-SNP site in human islets. Moreover, six CpG-SNPs, representing TCF7L2, KCNQ1, CDKN2A, ADCY5, WFS1 and HMGA2, were also associated with DNA methylation of surrounding CpG sites. Some of the type 2 diabetes CpG-SNP sites that exhibit differential DNA methylation were further associated with gene expression, alternative splicing events determined by splice index, and hormone secretion in the human islets. The 19 type 2 diabetes-associated CpG-SNPs are in strong linkage disequilibrium (r² > 0.8) with a total of 295 SNPs, including 91 CpG-SNPs. CONCLUSIONS/INTERPRETATION: Our results suggest that the introduction or removal of a CpG site may be a molecular mechanism through which some of the type 2 diabetes SNPs affect gene function via differential DNA methylation and consequently contributes to the phenotype of the disease.

Vanin-1 T26I polymorphism, hypertension and cardiovascular events in two large urban-based prospective studies in Swedes.

BACKGROUND AND AIMS: Vanin-1 (gene name VNN1) is an enzyme with pantetheinase activity generating the amino-thiol cysteamine which is implicated in the regulation of red-ox status through its effect on glutathione. We tested the hypothesis that the rs2294757 VNN1 T26I polymorphism could affect blood pressure (BP) levels, hypertension prevalence, and risk of incident cardiovascular events. METHODS AND RESULTS: The VNN1 T26I polymorphism was genotyped in 5664 participants of the cardiovascular cohort of the "Malmö Diet and Cancer" (MDC-CVA) study and successively in 17874 participants of the "Malmö Preventive project"(MPP). The incidence of cardiovascular events was monitored for an average of nearly 12 years of follow-up in the MDC-CVA and for 25 years in the MPP. Both before and after adjustment for sex, age and BMI in the MDC-CVA the polymorphism had a mild lowering effect on diastolic BP and hypertension, especially in females. However in MPP no effect on BP phenotypes was detectable. Before and after adjustment for major cardiovascular risk factors, the hazard ratio for incident ischemic stroke and coronary events in the MDC-CVA was not significantly different in carriers of different genotypes. CONCLUSIONS: Our data do not support a major role for the VNN1 T26I variant in determining BP level and incident ischemic events.

Genetic polymorphisms for estimating risk of atrial fibrillation: a literature-based meta-analysis.

BACKGROUND: Genetic polymorphisms associated with common aetiologically complex diseases have recently been identified through genome-wide association studies. Direct-to-consumer genetic testing for such polymorphisms, with provision of absolute genetic risk estimates, is marketed by several commercial companies. Polymorphisms associated with atrial fibrillation (AF) have shown relatively large risk estimates, but the robustness of such estimates across populations and study designs has not been investigated. DESIGN: A systematic literature review with meta-analysis and assessment of between-study heterogeneity was carried out for single-nucleotide polymorphisms (SNPs) in the six genetic regions associated with AF in genome-wide or candidate gene studies. RESULTS: Data were identified from 18 samples of European ancestry (n=12,100 cases, 115,702 controls) for the single-nucleotide polymorphisms (SNP) on chromosome 4q25 (rs220733), from 16 samples (n=12,694 cases, 132,602 controls) for the SNP on 16q22 (rs2106261) and from four samples (n=5272 cases, 59,725 controls) for the SNP in KCNH2 (rs1805123). Only the publications in which the associations were initially reported were identified for SNPs on 1q21 and in GJA5 and IL6R, why meta-analyses were not performed for those SNPs. In overall random-effects meta-analyses, association with AF was observed for both SNPs on chromosomes 4q25 [odds ratio (OR), 1.67; 95% CI, 1.50-1.86, P=2×10(-21)] and 16q22 (OR, 1.21; 95% CI, 1.13-1.29, P=1×10(-8)) from genome-wide studies, but not the SNP in KCNH2 from candidate gene studies (P=0.15). There was substantial effect heterogeneity across case-control and cross-sectional studies for both polymorphisms (I(2)=0.50-0.78, P<0.05), but not across prospective cohort studies (I(2)=0.39, P=0.15). Both polymorphisms were robustly associated with AF for each study design individually (P<0.05). CONCLUSIONS: In meta-analyses including up to 150,000 individuals, polymorphisms in two genetic regions were robustly associated with AF across all study designs but with substantial context-dependency of risk estimates.

Genetic prediction of postpartum diabetes in women with gestational diabetes mellitus.

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.

A myocardial infarction genetic risk score is associated with markers of carotid atherosclerosis.

OBJECTIVE: To assess whether or not a genetic risk score that was previously shown to be associated with myocardial infarction (MI) and coronary artery disease (CAD) is also associated with markers of carotid atherosclerosis. DESIGN: A total of 4022 middle-aged subjects from the general Swedish population were genotyped and individually assigned a genetic risk score based on 13 single-nucleotide polymorphisms (SNPs), previously associated with MI and CAD. The genetic score (Score-MI) was then related to carotid bulb intima-media thickness (IMT), common carotid artery (CCA) IMT and to the occurrence of carotid plaques in the study population. RESULTS: Score-MI was associated with IMT of the bulb (P < 0.001) and the CCA (P < 0.001) in unadjusted analyses, and with IMT of the bulb after adjustment for cardiovascular risk factors (P = 0.003). The effect size of Score-MI on IMT of the bulb was similar to that of LDL cholesterol. After adjustment for cardiovascular risk factors, Score-MI was also associated with the occurrence of carotid plaques (odds ratio per quintile of Score-MI = 1.11; 95% confidence interval 1.04-1.18; P = 0.001). In addition to SNPs with known effects on LDL levels, Score-MI showed nominal associations with increasing systolic blood pressure and decreasing C-reactive protein levels. CONCLUSIONS: This genetic risk score was independently associated with carotid bulb IMT and carotid plaques, providing evidence of an association with early markers of atherosclerosis. This might imply that the genetic MI risk conferred by the score is related to early atherosclerosis and that the risk score may identify at an early stage candidates at risk of developing intermediate phenotypes of atherosclerosis. Further studies should test whether or not assessing the genetic score could be valuable for early treatment decisions in these subjects.

A common variant upstream of the PAX6 gene influences islet function in man.

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.

Heritability and familiality of type 2 diabetes and related quantitative traits in the Botnia Study.

AIMS/HYPOTHESIS: To study the heritability and familiality of type 2 diabetes and related quantitative traits in families from the Botnia Study in Finland. METHODS: Heritability estimates for type 2 diabetes adjusted for sex, age and BMI are provided for different age groups of type 2 diabetes and for 34 clinical and metabolic traits in 5,810 individuals from 942 families using a variance component model (SOLAR). In addition, family means of these traits and their distribution across families are calculated. RESULTS: The strongest heritability for type 2 diabetes was seen in patients with age at onset 35-60 years (h (2) = 0.69). However, including patients with onset up to 75 years dropped the h (2) estimates to 0.31. Among quantitative traits, the highest h (2) estimates in all individuals and in non-diabetic individuals were seen for lean body mass (h (2) = 0.53-0.65), HDL-cholesterol (0.52-0.61) and suppression of NEFA during OGTT (0.63-0.76) followed by measures of insulin secretion (insulinogenic index [IG(30)] = 0.41-0.50) and insulin action (insulin sensitivity index [ISI] = 0.37-0.40). In contrast, physical activity showed rather low heritability (0.16-0.18), whereas smoking showed strong heritability (0.57-0.59). Family means of these traits differed two- to fivefold between families belonging to the lowest and highest quartile of the trait (p < 0.00001). CONCLUSIONS/INTERPRETATION: To detect stronger genetic effects in type 2 diabetes, it seems reasonable to restrict inclusion of patients to those with age at onset 35-60 years. Sequencing of families with extreme quantitative traits could be an important next step in the dissection of the genetics of type 2 diabetes.

A family history of diabetes is associated with reduced physical fitness in the Prevalence, Prediction and Prevention of Diabetes (PPP)-Botnia study.

AIMS/HYPOTHESIS: We studied the impact of a family history of type 2 diabetes on physical fitness, lifestyle factors and diabetes-related metabolic factors. METHODS: The Prevalence, Prediction and Prevention of Diabetes (PPP)-Botnia study is a population-based study in Western Finland, which includes a random sample of 5,208 individuals aged 18 to 75 years identified through the national Finnish Population Registry. Physical activity, dietary habits and family history of type 2 diabetes were assessed by questionnaires and physical fitness by a validated 2 km walking test. Insulin secretion and action were assessed based upon OGTT measurements of insulin and glucose. RESULTS: A family history of type 2 diabetes was associated with a 2.4-fold risk of diabetes and lower physical fitness (maximal aerobic capacity 29.2 +/- 7.2 vs 32.1 +/- 7.0, p = 0.01) despite having similar reported physical activity to that of individuals with no family history. The same individuals also had reduced insulin secretion adjusted for insulin resistance, i.e. disposition index (p < 0.001) despite having higher BMI (27.4 +/- 4.6 vs 26.0 +/- 4.3 kg/m(2), p < 0.001). CONCLUSIONS/INTERPRETATION: Individuals with a family history of type 2 diabetes are characterised by lower physical fitness, which cannot solely be explained by lower physical activity. They also have an impaired capacity of beta cells to compensate for an increase in insulin resistance imposed by an increase in BMI. These defects should be important targets for interventions aiming at preventing type 2 diabetes in individuals with inherited susceptibility to the disease.

An investigation of serum concentration of apoM as a potential MODY3 marker using a novel ELISA.

OBJECTIVE: To investigate the fitness of serum apolipoprotein M (apoM) concentration as a marker for maturity-onset diabetes of the young 3 (MODY3). STUDY DESIGN AND SUBJECTS: This study consisted of two parts. A family study included 71 carriers of the P291fsinsC mutation in hepatocyte nuclear factor-1alpha (HNF-1alpha) from the Finnish Botnia study, 53 of whom were diabetic, and 75 matched family controls. A second, case-control study included 24 MODY3 patients, 17 healthy MODY3 mutation carriers, 11 MODY1 patients, 18 type 2 diabetes patients and 19 healthy control individuals. Subjects in the case-control study were recruited from the Botnia study or the Clinic of Endocrinology, Malmö University Hospital. Serum apoM levels were measured using a novel ELISA based on two monoclonal apoM antibodies. RESULTS: In the family study, mean serum apoM was 10% lower in female carriers of the P291fsinsC mutation compared to the family controls (P = 0.0058), a difference which remained significant after adjustment for diabetes status. There was no observed difference between groups for men. In the case-control study, no significant difference in apoM concentration was observed between MODY3 and type 2 diabetes patients, neither before nor after adjustment for total cholesterol. CONCLUSIONS: Female carriers of the P291fsinsC mutation in HNF-1alpha displayed slightly lower apoM serum levels. This difference is too small for apoM to be reliably employed as a biomarker for HNF-1alpha mutation status.

Prediction of postpartum diabetes in women with gestational diabetes mellitus.

AIMS/HYPOTHESIS: We studied the incidence of postpartum diabetes after gestational diabetes mellitus and investigated biochemical and clinical predictors of postpartum diabetes. METHODS: We monitored 174 women with gestational diabetes by performing oral glucose tolerance tests during pregnancy as well as 1, 2 and 5 years postpartum. Women who developed impaired fasting glucose, impaired glucose tolerance or diabetes were compared with women who remained normoglycaemic at 5 years. Insulinogenic index, disposition index and HOMA-beta cell index were used to assess beta cell function; insulin resistance was estimated by HOMA index of insulin resistance. RESULTS: At 5 years postpartum, 30% of the women had developed diabetes and 51% some form of abnormal glucose tolerance. Women who developed diabetes had higher fasting glucose and HbA(1c) during pregnancy than those who remained normoglycaemic. They also had lower HOMA-beta cell index, insulinogenic index and disposition index than the normoglycaemic women. HbA(1c) and fasting glucose during pregnancy as well as the number of previous pregnancies and family history of diabetes were independent predictors of postpartum diabetes. HbA(1c) > or =4.7% (Swedish Mono S) or > or =5.7% (National Glycohemoglobin Standardization Program) and fasting blood glucose > or =5.2 mmol/l were associated with a four- to sixfold increased risk. CONCLUSIONS/INTERPRETATION: Among women with gestational diabetes mellitus, those at risk of future diabetes can be identified by HbA(1c) and fasting glucose values in the upper normal range during pregnancy. A family history of diabetes and previous pregnancies further increase this risk.