Genetically predicted 17beta-estradiol and cardiovascular risk factors in women: a Mendelian randomization analysis using young women in Hong Kong and older women in the Guangzhou Biobank Cohort Study

Implicating genes, pleiotropy, and sexual dimorphism at blood lipid loci through multi-ancestry meta-analysis

BACKGROUND

Genetic variants within nearly 1000 loci are known to contribute to modulation of blood lipid levels. However, the biological pathways underlying these associations are frequently unknown, limiting understanding of these findings and hindering downstream translational efforts such as drug target discovery.

RESULTS

To expand our understanding of the underlying biological pathways and mechanisms controlling blood lipid levels, we leverage a large multi-ancestry meta-analysis (N = 1,654,960) of blood lipids to prioritize putative causal genes for 2286 lipid associations using six gene prediction approaches. Using phenome-wide association (PheWAS) scans, we identify relationships of genetically predicted lipid levels to other diseases and conditions. We confirm known pleiotropic associations with cardiovascular phenotypes and determine novel associations, notably with cholelithiasis risk. We perform sex-stratified GWAS meta-analysis of lipid levels and show that 3-5% of autosomal lipid-associated loci demonstrate sex-biased effects. Finally, we report 21 novel lipid loci identified on the X chromosome. Many of the sex-biased autosomal and X chromosome lipid loci show pleiotropic associations with sex hormones, emphasizing the role of hormone regulation in lipid metabolism.

CONCLUSIONS

Taken together, our findings provide insights into the biological mechanisms through which associated variants lead to altered lipid levels and potentially cardiovascular disease risk.

Associations of growth from birth to puberty with blood pressure and lipid profile at ~17.5 years: evidence from Hong Kong's "Children of 1997" birth cohort

The role of early growth in later health is controversial. We examined the associations of growth at different phases from birth to puberty with blood pressure and lipid profile at ~17.5 years. In the population-representative "Children of 1997" birth cohort, growth was measured as (i) weight-for-age z score (WAZ) at birth and WAZ gains from 0 to 2 and 2 to 8 years and (ii) body-mass-index-for-age z score (BAZ) and length/height-for-age z score (LAZ) at 3 months and BAZ and LAZ gains from 3 months to 3 years, 3 to 8 years and 8 to 14 years, based on the World Health Organization growth standards/references. Adjusted partial least squares regression was used to assess simultaneously the associations of growth with height-, age- and sex-specific systolic (SBPZ) and diastolic blood pressure z scores (DBPZ), low- (LDL) and high-density lipoprotein (HDL) and triglycerides (TG) at ~17.5 years. Among 3410 children, higher WAZ, BAZ and LAZ gains from initial size to 8 years were associated with higher SBPZ. Higher gains in WAZ and BAZ from 2 to 8 years were consistently associated with higher DBPZ, LDL and TG and lower HDL. Lower LAZ at 3 months and higher LAZ gain from 3 months to 3 years were associated with lower HDL and higher TG. Greater growth in weight, body mass index and length/height had negative associations with blood pressure and lipid profile at ~17.5 years, but the differences by growth measure, phase and outcome suggest a complex underlying process.

Age-specific reference ranges of serum anti-müllerian hormone in healthy women and its application in diagnosis of polycystic ovary syndrome: a population study

OBJECTIVE

To establish the age-specific centiles of serum anti-müllerian hormone (AMH) levels in Chinese women, and to explore the use of multiples of median (MoM) AMH levels for the diagnosis of polycystic ovary syndrome (PCOS).

DESIGN

An observational study.

SETTING

University-affiliated hospitals and community clinics.

POPULATION

We included 3137 healthy women aged 20-44 years recruited prospectively or who had archived serum samples from previous research projects. Another validation cohort of 751 women with PCOS as well as ovulatory controls, which was a convenient sample of women attending for infertility or menstrual disorders, was also studied.

METHODS

The serum samples were assayed for AMH by the automated Access AMH assay.

MAIN OUTCOME MEASURES

Age-specific reference ranges were constructed on the primary cohort with the Lambda-Mu-Sigma method. The MoM AMH of each subject in the validation cohort was calculated.

RESULTS

Centile curves of serum AMH level against age were established. MoM AMH was significantly higher in women with PCOS than in controls (P < 0.05). The area under the ROC curve was 0.852 (95% confidence interval [CI] 0.825-0.877) (P < 0.0001) for discriminating women with PCOS from ovulatory controls by MoM AMH.

CONCLUSIONS

We established a set of year-by-year age-specific reference ranges of serum AMH levels in Chinese women. The MoM AMH derived from this set of reference ranges is a promising tool to replace antral follicle count in the diagnosis of PCOS.

TWEETABLE ABSTRACT

A set of age-specific reference ranges of AMH levels was established in Chinese women. Multiples of median AMH may be used to diagnose PCOS.

Mendelian randomization: a novel approach for the prediction of adverse drug events and drug repurposing opportunities

Identification of unintended drug effects, specifically drug repurposing opportunities and adverse drug events, maximizes the benefit of a drug and protects the health of patients. However, current observational research methods are subject to several biases. These include confounding by indication, reverse causality and missing data. We propose that Mendelian randomization (MR) offers a novel approach for the prediction of unintended drug effects. In particular, we advocate the synthesis of evidence from this method and other approaches, in the spirit of triangulation, to improve causal inferences concerning drug effects. MR addresses some of the limitations associated with the existing methods in this field. Furthermore, it can be applied either before or after approval of the drug, and could therefore prevent the potentially harmful exposure of patients in clinical trials and beyond. The potential of MR as a pharmacovigilance and drug repurposing tool is yet to be realized, and could both help prevent adverse drug events and identify novel indications for existing drugs in the future.

Endogenous androgen exposures and ischemic heart disease, a separate sample Mendelian randomization study

BACKGROUND

Evolutionary biology suggests growth and reproduction trade-off against longevity. Correspondingly estrogen supplementation failed to increase lifespan. Testosterone supplementation is widely used by older men, although regulators have warned of its cardiovascular risk. No large trial of testosterone exists. We examined how genetic determinants of up-regulation (follicle-stimulating hormone (FSH)) and down-regulation (anti-Müllerian hormone (AMH) and testicular dysgenesis syndrome (TDS)) of mainly the male reproductive system are associated with ischemic heart disease (IHD).

METHODS

Separate sample instrumental variable analysis with genetic instruments, i.e., Mendelian randomization, was used to obtain unconfounded estimates using large case-control studies of coronary artery disease/myocardial infarction (CAD/MI) with extensive genotyping, i.e., CARDIoGRAMplusC4D (64,374 CAD/MI cases, 130,681controls), or CARDIoGRAMplusC4D 1000 Genomes (60,801 cases, 123,504 controls).

RESULTS

Genetically predicted FSH was positively associated with CAD/MI (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.03 to 1.13 per mIU/mL FSH). Genetically predicted AMH and TDS were inversely associated with CAD/MI (OR 0.93, 95% CI 0.87 to 0.998 per ng/mL log AMH and OR 0.89, 95% CI 0.81 to 0.98 per log OR higher risk of TDS).

CONCLUSIONS

As expected from evolutionary biology, genetically predicted FSH, related to higher androgens in men and women, was positively associated with IHD, while genetically predicted AMH and TDS, related to lower androgens in men, were inversely associated with IHD. Androgens might be a modifiable causal factor underlying men's greater vulnerability to IHD, with corresponding implications for use of testosterone supplementation as well as for prevention and treatment of IHD.