Publications

Association testing of multiple correlated phenotypes offers better power than univariate analysis of single traits. We analyzed 6,600 individuals from two population-based cohorts with both genome-wide SNP data and serum metabolomic profiles. From the observed correlation structure of 130 metabolites measured by nuclear magnetic resonance, we identified 11 metabolic networks and performed a multivariate genome-wide association analysis. We identified 34 genomic loci at genome-wide significance, of which 7 are novel. In comparison to univariate tests, multivariate association analysis identified nearly twice as many significant associations in total. Multi-tissue gene expression studies identified variants in our top loci, SERPINA1 and AQP9, as eQTLs and showed that SERPINA1 and AQP9 expression in human blood was associated with metabolites from their corresponding metabolic networks. Finally, liver expression of AQP9 was associated with atherosclerotic lesion area in mice, and in human arterial tissue both SERPINA1 and AQP9 were shown to be upregulated (6.3-fold and 4.6-fold, respectively) in atherosclerotic plaques. Our study illustrates the power of multi-phenotype GWAS and highlights candidate genes for atherosclerosis.

OBJECTIVE To quantitatively assess the strength and shape of the association between blood 25-hydroxy vitamin D [25(OH)D] levels and incident risk of type 2 diabetes. RESEARCH DESIGN AND METHODS A systematic search of the MEDLINE and Embase databases and a hand search of references from original reports were conducted up to 31 October 2012. Prospective observational studies that assessed the association between blood levels of 25(OH)D and risk of incident type 2 diabetes were included for meta-analysis. DerSimonian and Laird’s random-effects model was used. A quadratic spline regression analysis was used to examine the shape of the association with a generalized least-squares trend test performed for the dose-response relation. RESULTS A total of 21 prospective studies involving 76,220 participants and 4,996 incident type 2 diabetes cases were included for meta-analysis. Comparing the highest to the lowest category of 25(OH)D levels, the summary relative risk for type 2 diabetes was 0.62 (95% CI 0.54–0.70). A spline regression model showed that higher 25(OH)D levels were monotonically associated with a lower diabetes risk. This inverse association did not differ by sex, duration of follow-up, study sample size, diabetes diagnostic criteria, or 25(OH)D assay method. A linear trend analysis showed that each 10 nmol/L increment in 25(OH)D levels was associated with a 4% lower risk of type 2 diabetes (95% CI 3–6; P for linear trend < 0.0001). CONCLUSIONS Our meta-analysis showed an inverse and significant association between circulating 25(OH)D levels and risk of type 2 diabetes across a broad range of blood 25(OH)D levels in diverse populations.

Abstract Objective To evaluate the association of plant-based diet index (PDI) with early onset of natural menopause in the Nurses’ Health Study (NHS) and Nurses’ Health Study II (NHSII). Methods We conducted a prospective study with a mean follow-up time of 20 years among premenopausal women living across the US. Participants of the NHS ( n = 121,701) and NHSII ( n = 116,429) were included from 1984 (age mean [standard deviation]; 44.9 [4.3]) and 1991 (age mean [standard deviation]; 36.4 [4.6]), respectively. Early menopause was self-reported and defined as natural menopause before age 45 years. PDI was derived from semiquantitative food frequency questionnaires administered every 4 years. Cox proportional hazards models were used to assess the association between PDI in quintiles and early menopause in NHS and NHSII separately, and fixed-effect models to pool the results from both cohorts. Results During follow-up, 715 and 2,185 women experienced early natural menopause in NHS and NHSII, respectively. After adjustment for potential confounders, no association was observed between PDI and incidence of early natural menopause in either cohort, or when pooling the results from both cohorts, with an exception for unhealthy plant-based diet index which was associated with higher risk of early menopause with increasing levels of consumption (P trend = 0.04). Conclusion Adherence to PDI was not associated with timing of menopause while unhealthy plant-based diet might be associated with higher risk of experiencing early menopause.

Background— The results of cohort studies relating sodium (Na) intake to blood pressure–related cardiovascular disease (CVD) are inconsistent. To understand whether methodological issues account for the inconsistency, we reviewed the quality of these studies. Methods and Results— We reviewed cohort studies that examined the association between Na and CVD. We then identified methodological issues with greatest potential to alter the direction of association (reverse causality, systematic error in Na assessment), some potential to alter the direction of association (residual confounding, inadequate follow-up), and the potential to yield false null results (random error in Na assessment, insufficient power). We included 26 studies with 31 independent analyses. Of these, 13 found direct associations between Na and CVD, 8 found inverse associations, 2 found J-shaped associations, and 8 found null associations only. On average there were 3 to 4 methodological issues per study. Issues with greater potential to alter the direction of association were present in all but 1 of the 26 studies (systematic error, 22; reverse causality, 16). Issues with lesser potential to alter the direction of association were present in 18 studies, whereas those with potential to yield false null results were present in 23. Conclusions— Methodological issues may account for the inconsistent findings in currently available observational studies relating Na to CVD. Until well-designed cohort studies in the general population are available, it remains appropriate to base Na guidelines on the robust body of evidence linking Na with elevated blood pressure and the few existing general population trials of the effects of Na reduction on CVD.

No abstract is provided for this article.

Abstract Understanding the biological mechanisms behind multimorbidity patterns in adolescence is important as they may act as intermediary risk factor for long-term health. We aimed to explore relationship between prenatal exposures and adolescent’s psycho-cardiometabolic intermediary traits mediated through epigenetic biomarkers, using structural equation modelling (SEM). We used data from mother-child dyads from pregnancy and adolescents at 16–17 years from two prospective cohorts: Northern Finland Birth Cohort 1986 (NFBC1986) and Raine Study from Australia. Factor analysis was applied to generate two different latent factor structures: a) prenatal exposures and b) adolescence psycho-cardiometabolic intermediary traits. Furthermore, three types of epigenetic biomarkers were included: 1) DNA methylation score for maternal smoking during pregnancy (DNAmMSS), 2) DNAm age estimate PhenoAge and 3) DNAm estimate for telomere length (DNAmTL). We observed similar factor structure was observed between both cohorts yielding three prenatal factors BMI (Body Mass Index), SOP (Socio-Obstetric-Profile) and Lifestyle, and four adolescent factors: Anthropometric, Insulin-Triglycerides, Blood Pressure and Mental health. In the SEM pathways, stronger direct effects of F1 prenatal -BMI (NFBC1986 = ß: 0.27; Raine = ß: 0.39) and F2 prenatal -SOP (ß: -0.11) factors were observed on adolescent psycho-cardiometabolic multimorbidity. The indirect effect of the prenatal latent factors through epigenetic markers was mediated from DNAmTL and DNAmMSS going through PhenoAge (NFBC1986 = ß: 0.04; Raine = ß: 0.14), consistently in both cohorts ( P < 0.001). The present study exemplifies an evidence-based approach validated in two birth cohorts to demonstrate consistent shared influences of prenatal exposures mediated through epigenetic markers in the offspring on their psycho-cardiometabolic multimorbidity in adolescence.