Transcriptome-wide association analyses identify an association between ARL14EP and polycystic ovary syndrome

Bivariate genome-wide association study of circulating fibrinogen and C-reactive protein levels

BACKGROUND

Fibrinogen and C-reactive protein (CRP) play an important role in inflammatory pathways and share multiple genetic loci reported in previously published genome-wide association studies (GWAS), highlighting their common genetic background. Leveraging the shared biology may identify further loci pleiotropically associated with both fibrinogen and CRP.

OBJECTIVES

To identify novel genetic variants that are pleiotropic and associated with both fibrinogen and CRP, by integrating both phenotypes in a bivariate GWAS by using a multitrait GWAS.

METHODS

We performed a bivariate GWAS to identify further pleiotropic genetic loci, using summary statistics of previously published GWAS on fibrinogen (n = 120 246) from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium, consisting of European ancestry samples and CRP (n = 363 228) from UK Biobank, including 5 different population groups. The main analysis was performed using metaUSAT and N-GWAMA. We conducted replication for novel CRP associations to test the robustness of the findings using an independent GWAS for CRP (n = 148 164). We also performed colocalization analysis to compare the associations in identified loci for the 2 traits and Genotype-Tissue Expression data.

RESULTS

We identified 87 pleiotropic loci that overlapped between metaUSAT and N-GWAMA, including 23 previously known for either fibrinogen or CRP, 58 novel loci for fibrinogen, and 6 novel loci for both fibrinogen and CRP. Overall, there were 30 pleiotropic and novel loci for both traits, and 7 of these showed evidence of colocalization, located in or near ZZZ3, NR1I2, RP11-72L22.1, MICU1, ARL14EP, SOCS2, and PGM5. Among these 30 loci, 13 replicated for CRP in an independent CRP GWAS.

CONCLUSION

Bivariate GWAS identified additional associated loci for fibrinogen and CRP. This analysis suggests fibrinogen and CRP share a common genetic architecture with many pleiotropic loci.

New insights into the (epi)genetics of twinning

Spontaneous dizygotic (DZ) twins, i.e. twins conceived without the use of ARTs, run in families and their prevalence varies widely around the globe. In contrast, monozygotic (MZ) twins occur at a constant rate across time and geographical regions and, with some rare exceptions, do not cluster in families. The leading hypothesis for MZ twins, which arise when a zygote splits during preimplantation stages of development, is random occurrence. We have found the first series of genes underlying the liability of being the mother of DZ twins and have shown that being an MZ twin is strongly associated with a stable DNA methylation signature in child and adult somatic tissues. Because identical twins keep this molecular signature across the lifespan, this discovery opens up completely new possibilities for the retrospective diagnosis of whether a person is an MZ twin whose co-twin may have vanished in the early stages of pregnancy. Here, we summarize the gene finding results for mothers of DZ twins based on genetic association studies followed by meta-analysis, and further present the striking epigenetic results for MZ twins.

Pathophysiological Effects of Contemporary Lifestyle on Evolutionary-Conserved Survival Mechanisms in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is increasingly being characterized as an evolutionary mismatch disorder that presents with a complex mixture of metabolic and endocrine symptoms. The Evolutionary Model proposes that PCOS arises from a collection of inherited polymorphisms that have been consistently demonstrated in a variety of ethnic groups and races. In utero developmental programming of susceptible genomic variants are thought to predispose the offspring to develop PCOS. Postnatal exposure to lifestyle and environmental risk factors results in epigenetic activation of developmentally programmed genes and disturbance of the hallmarks of health. The resulting pathophysiological changes represent the consequences of poor-quality diet, sedentary behaviour, endocrine disrupting chemicals, stress, circadian disruption, and other lifestyle factors. Emerging evidence suggests that lifestyle-induced gastrointestinal dysbiosis plays a central role in the pathogenesis of PCOS. Lifestyle and environmental exposures initiate changes that result in disturbance of the gastrointestinal microbiome (dysbiosis), immune dysregulation (chronic inflammation), altered metabolism (insulin resistance), endocrine and reproductive imbalance (hyperandrogenism), and central nervous system dysfunction (neuroendocrine and autonomic nervous system). PCOS can be a progressive metabolic condition that leads to obesity, gestational diabetes, type two diabetes, metabolic-associated fatty liver disease, metabolic syndrome, cardiovascular disease, and cancer. This review explores the mechanisms that underpin the evolutionary mismatch between ancient survival pathways and contemporary lifestyle factors involved in the pathogenesis and pathophysiology of PCOS.

Updated experimental cellular models to study polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) develops due to hormonal imbalance and hyperandrogenism. Animal models are widely used to study PCOS because they mimic essential characteristics of human PCOS; however, the pathogenesis of PCOS remains unclear. Different sources of novel drugs are currently being screened as therapeutic strategies to alleviate PCOS and its symptoms. Simplified cell line in-vitro models could be preliminarily used to screen the bioactivity of various drugs. This review describes different cell line models focusing on the PCOS condition and its complications. Therefore, the bioactivity of the drugs could be preliminarily screened in a cell line model before moving to higher animal models.