Replication of association of DENND1A and THADA variants with polycystic ovary syndrome in European cohorts.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a complex endocrine disorder with a strong familial component. PCOS is characterised by hyperandrogenaemia and irregular menses. A recent genome-wide association study (GWAS) of PCOS in a Chinese cohort identified three reproducible PCOS susceptibility loci mapping to 2p16.3 (luteinising hormone/choriogonadotropin receptor; LHCGR), 2p21 (thyroid associated protein; THADA), and 9q33.3 (DENN/MADD domain containing 1A; DENNDIA). The impact of these loci in non-Chinese PCOS cohorts remains to be determined. METHODS AND RESULTS: The study tested association with PCOS of seven single nucleotide polymorphisms mapping to the three Chinese PCOS loci in two European derived PCOS cohorts (cohort A = 939 cases and 957 controls; cohort B = 535 cases and 845 controls). Cases fulfilled the National Institute of Child Health & Human Development criteria for PCOS. Variation in DENND1A was strongly associated with PCOS in the study cohort (p(combined cohorts)=10(-8)); multiple variants in THADA were also associated with PCOS, while there was no significant evidence for association of LHCGR variation with PCOS. The present study had >80% power to detect an effect of similar size as was observed by Chen et al for DENND1A and THADA, but reduced power (at <40%) for LHCGR at p=0.0001. The study had sufficient power (57-88%) for LHCGR at p=0.01. CONCLUSIONS: At least two of the PCOS susceptibility loci identified in the Chinese PCOS GWAS (DENND1A and THADA) are also associated with PCOS in European derived populations, and are therefore likely to be important in the aetiology of PCOS regardless of ethnicity. The analysis of the LHCGR gene was not sufficiently powered to detect modest effects.

Association study of CYP17 and HSD11B1 in polycystic ovary syndrome utilizing comprehensive gene coverage.

Cytochrome P450-C17 enzyme (CYP17) is an important component of the androgen synthesis pathway, a pathway that is dysfunctional in polycystic ovary syndrome (PCOS). Variation in 11-beta hydroxysteroid dehydrogenase (HSD11B1) is associated with cortisone reductase deficiency, a condition with a phenotype similar to PCOS. Both CYP17 and HSD11B1 genes have been previously studied for their possible relationship with PCOS, yielding inconsistent results. In this study, we evaluated the association between variation in these genes and PCOS. Two-hundred and eighty-seven Caucasian PCOS women and 187 Caucasian controls were genotyped for single nucleotide polymorphisms (SNPs) that were specifically chosen to allow full coverage of CYP17 and HSD11B1, including four SNPs in CYP17 and eight SNPs in HSD11B1. SNP and haplotype association analyses were conducted. Our results indicate that variants in the two genes are not associated with PCOS, or with the quantitative traits characteristic of PCOS, suggesting that these genes are not major risk factors for the syndrome.

Early embryonic androgen exposure induces transgenerational epigenetic and metabolic changes.

Androgen excess is a central feature of polycystic ovary syndrome (PCOS), which affects 6% to 10% of young women. Mammals exposed to elevated androgens in utero develop PCOS-like phenotypes in adulthood, suggesting fetal origins of PCOS. We hypothesize that excess androgen exposure during early embryonic development may disturb the epigenome and disrupt metabolism in exposed and unexposed subsequent generations. Zebrafish were used to study the underlying mechanism of fetal origins. Embryos were exposed to androgens (testosterone and dihydrotestosterone) early at 26 to 56 hours post fertilization or late at 21 to 28 days post fertilization. Exposed zebrafish (F0) were grown to adults and crossed to generate unexposed offspring (F1). For both generations, global DNA methylation levels were examined in ovaries using a luminometric methylation assay, and fasting and postprandial blood glucose levels were measured. We found that early but not late androgen exposure induced changes in global methylation and glucose homeostasis in both generations. In general, F0 adult zebrafish exhibited altered global methylation levels in the ovary; F1 zebrafish had global hypomethylation. Fasting blood glucose levels were decreased in F0 but increased in F1; postprandial glucose levels were elevated in both F0 and F1. This androgenized zebrafish study suggests that transient excess androgen exposure during early development can result in transgenerational alterations in the ovarian epigenome and glucose homeostasis. Current data cannot establish a causal relationship between epigenetic changes and altered glucose homeostasis. Whether transgenerational epigenetic alteration induced by prenatal androgen exposure plays a role in the development of PCOS in humans deserves study.

Metabolic and cardiovascular genes in polycystic ovary syndrome: a candidate-wide association study (CWAS).

The role of metabolic disturbance in polycystic ovary syndrome (PCOS) has been well established, with insulin resistance and the resulting compensatory hyperinsulinemia thought to promote hyperandrogenemia. Genome-wide association studies (GWAS) have established a large number of loci for metabolic conditions such as type 2 diabetes and obesity. A subset of these loci has been investigated for a role in PCOS; these studies generally have not revealed a confirmed role for these loci in PCOS risk. However, a large scale investigation of genes related to these pathways has not previously been performed. We conducted a two stage case control association study of 121,715 single nucleotide polymorphisms (SNPs) selected to represent susceptibility loci associated with traits such as type 2 diabetes, obesity measures, lipid levels and cardiovascular function using the Cardio-Metabochip in 847 PCOS cases and 845 controls. Several hypothesis-generating associations with PCOS were observed (top SNP rs2129107, P=3.8×10(-6)). We did not find any loci definitively associated with PCOS after strict correction for multiple testing, suggesting that cardio-metabolic loci are not major risk factors underlying the susceptibility to PCOS.

Steroidogenic regulatory factor FOS is underexpressed in polycystic ovary syndrome (PCOS) adipose tissue and genetically associated with PCOS susceptibility.

CONTEXT: Polycystic ovary syndrome (PCOS) is a heterogeneous common genetic disorder characterized by hyperandrogenemia and insulin resistance. Alterations in gene expression profiles of the ovary and adipose tissue identified the candidate gene FBJ murine osteosarcoma viral oncogene homolog (FOS) for further investigation of expression changes in metabolic tissues and genetic studies. OBJECTIVE: The objective of the study was to confirm the underexpression of the FOS gene in sc adipose and determine whether variants in this gene are risk factors for PCOS. DESIGN: RT-PCR was performed in sc fat from women with and without PCOS. Genotyping of single-nucleotide polymorphisms in the FOS locus was performed to test for association with PCOS. SETTING: The study was conducted at a tertiary care academic institution. PARTICIPANTS: Twenty-two PCOS and 13 control subjects were recruited for gene expression studies. We assembled a discovery genotyping cohort of 354 cases and 161 controls and a replication cohort of 476 cases and 315 controls, all of whom were Caucasian. MAIN MEASUREMENTS: Gene expression by quantitative real-time RT-PCR, FOS genotype, and PCOS status were measured. RESULTS: FOS expression was confirmed to be reduced in PCOS adipose tissue. Three single-nucleotide polymorphisms were significantly associated with PCOS in the discovery cohort (rs8006998, P = 0.0031; rs8013918, P = 0.0006; rs8013942, P = 0.0087). rs8006998 was also associated with PCOS in the replication cohort (P = 0.013). CONCLUSIONS: Differential gene expression in sc fat and genetic association at the FOS locus in PCOS subjects implicates a role for this transcription factor in PCOS. FOS dysfunction may be a common factor between hyperandrogenism and insulin resistance.