Haplotype-based case-control study of estrogen receptor alpha (ESR1) gene and pregnancy-induced hypertension

Genetic variations in estrogen and progesterone pathway genes in preeclampsia patients and controls in Bavaria

PURPOSE

Hypertensive pregnancy disorders and preeclampsia are major causes of maternal and fetal morbidity and mortality worldwide. Many different organs are involved in the diseases' clinical phenotype. The underlying mechanism is still unknown, with a possible genetic component. This case-control study investigated effects on the risk of preeclampsia of genetic variations (single nucleotide polymorphisms, SNPs) in the estrogen and progesterone pathway genes.

METHODS

The study included 167 patients with preeclampsia and 115 healthy controls from the "Franconian Maternal Health Evaluation Studies" (FRAMES). All patients completed an epidemiological questionnaire, data from which were correlated with prospective data on pregnancy and labor. DNA was isolated from blood samples and genotyping was done by PCR. Variants in the aromatase gene CYP19A1 (rs10046, rs4646), progesterone receptor gene (rs1042838, rs10895068), and estrogen receptor-α gene (rs488133) were examined, and the genotype distribution in the two groups was analyzed statistically.

RESULTS

A significant difference in the distribution frequency of genotypes between preeclampsia patients and controls was identified in one of the five SNPs. For rs10895068 in the progesterone receptor gene, genotype G/A was significantly more frequent among cases than controls (P = 0.023). No significant differences between the two cohorts were found in the other SNPs.

CONCLUSIONS

This study showed a significant association between only one SNP in the progesterone receptor and preeclampsia. Other studies have also noted genetic aspects of preeclampsia. The underlying mechanism and causal relationship are not yet known, and further research is needed to explain the extent of genetic variations and the causal relationship in preeclampsia.

SRC-1 Regulates Blood Pressure and Aortic Stiffness in Female Mice

Framingham Heart Study suggests that dysfunction of steroid receptor coactivator-1 may be involved in the development of hypertension. However, there is no functional evidence linking steroid receptor coactivator-1 to the regulation of blood pressure. We used immunohistochemistry to map the expression of steroid receptor coactivator-1 protein in mouse brain, especially in regions implicated in the regulation of blood pressure. Steroid receptor coactivator-1 protein was found in central amygdala, medial amygdala, supraoptic nucleus, arcuate nucleus, ventromedial, dorsomedial, paraventricular hypothalamus, and nucleus of the solitary tract. To determine the effects of steroid receptor coactivator-1 protein on cardiovascular system we measured blood pressures, blood flow velocities, echocardiographic parameters, and aortic input impedance in female steroid receptor coactivator-1 knockout mice and their wild type littermates. Steroid receptor coactivator-1 knockout mice had higher blood pressures and increased aortic stiffness when compared to female wild type littermates. Additionally, the hearts of steroid receptor coactivator-1 knockout mice seem to consume higher energy as evidenced by increased impedance and higher heart rate pressure product when compared to female wild type littermates. Our results demonstrate that steroid receptor coactivator-1 may be functionally involved in the regulation of blood pressure and aortic stiffness through the regulation of sympathetic activation in various neuronal populations.

Estrogen Receptor Alpha (ESR1) Gene Polymorphisms in Pre-eclamptic Saudi Patients

OBJECTIVES

Pre-eclampsia causes maternal mortality worldwide. Estrogen receptor alpha (ESR1) gene polymorphisms were responsible for cardiovascular diseases. This case control study was conducted to investigate whether 2 polymorphic genes of ESR1 are associated with pre-eclampsia among Saudi women in Madina city, Saudi Arabia.

METHODS

Blood samples from 97 pre-eclamptic and 94 healthy pregnant women were analyzed using restriction fragment length polymorphism-polymerase chain reaction method. All the subjects were recruited randomly from outpatient clinics of Madina Maternity Children Hospital (MMCH), Madina, Saudi Arabia, between Dec. 2012 and Jan. 2014.

RESULTS

There was no association between pre-eclampsia and PvuII and XbaI ESR1 gene polymorphisms individually. TT/AA and TT/AG genotype combination existed significantly in pre-eclamptic patients compared to control. The frequency of PvuII and XbaI combined TT/AA genotypes between pre-eclamptic women was 36.1% vs 9.6%, however, frequency of PvuII and XbaI combined TT/AG genotypes between pre-eclamptic women was 3.1% vs 17%, compared to control. The homozygous T-A haplotype carriers showed high pre-eclampsia risk, independent of pregnancy, BMI and smoking status (adjusted odds ratio (OR): 3.26, 95% confidence interval (CI):1.71-9.21). The heterozygous T-A haplotype carriers did not differ from that of non-carriers (adjusted OR: 1.12, 95% CI: 0.47-2.75). No association was observed between pre-eclampsia and T-G, C-G and C-A haplotype of PvuII and XbaIESR1 gene polymorphisms.

CONCLUSIONS

T-A haplotype of homozygous associated with pre eclampsia not heterozygous carriers of ESR 1 PvuII and XbaI gene polymorphisms elicited high risk of pre-eclampsia. GG genotype of XbaI polymorphism decreased pre-eclampsia risk. Further studies using larger sample size are recommended to investigate the ESR 1 gene polymorphisms associated with pre-eclampsia.

Analysis of sex hormone genes reveals gender differences in the genetic etiology of blood pressure salt sensitivity: the GenSalt study

BACKGROUND

We examined the association between 799 single-nucleotide polymorphisms in 39 sex hormone genes and blood pressure (BP) responses to a dietary-sodium intervention.

METHODS

A 7-day low-sodium feeding study (51.3 mmol sodium/day) followed by a 7-day high-sodium feeding study (307.8 mmol sodium/day) was conducted among 1,906 Han Chinese participants. Nine BP measurements were obtained at baseline and the end of each intervention period using a random-zero sphygmomanometer.

RESULTS

Among men, absolute BP responses to sodium interventions decreased with the number of minor alleles of estrogen receptor 1 (ESR1) markers rs9340844, rs9397453, rs9371562, rs9397459, and rs9383951. For example, mean diastolic blood pressure (DBP) responses to low-sodium intervention (95% confidence interval) were -2.67 (-3.13, -2.22) mm Hg among those with the rs9397453 C/C genotype, -1.23 (-1.98, -0.48) mm Hg among those with the C/T genotype, and 0.08 (-2.31, 2.47) mm Hg among those with the T/T genotype (P = 1×10(-4); false discovery rate (FDR)-q = 0.04). Mean DBP responses to high sodium according to the rs9397453 genotypes were 1.46 (1.03, 1.89) mm Hg among those with C/C, 0.19 (-0.54, 0.91) mm Hg among those with C/T, and -1.10 (-2.82, 0.61) mm Hg among those with T/T (P = 2×10(-4); FDR-q = 0.04). Similar trends were noted for the association between these ESR1 variants and SBP responses to the dietary intervention. There were no significant associations between sex hormone gene variants and salt sensitivity in women, with genotype-gender interactions noted for the ESR1 markers that achieved significance in men.

CONCLUSIONS

We identified strong, consistent associations between ESR1 gene variants and salt sensitivity in men. Our results support a gender-specific role for ESR1 in the etiology of this complex trait.

Estrogen synthesis genes CYP19A1, HSD3B1, and HSD3B2 in hypertensive disorders of pregnancy

Hypertension in pregnancy is a multifactorial disorder caused by a complex combination of environmental factors and several predisposing genes. Since estrogen modulates placental vascular development, estrogen synthases are considered plausible candidate genes. The aim of this haplotype-based case-control study was to estimate whether polymorphisms of the maternal estrogen synthesis genes (CYP19A1, HSD3B1 and HSD3B2) are associated with preeclampsia (PE) and gestational hypertension (GH). To examine the genetic markers in 69 PE and 62 GH patients and in 155 age-matched, primiparous, healthy control subjects, genotyping of 5 SNPs for the CYP19A1 gene (rs1870049, rs936306, rs700518, rs700519, and rs4646), 3 SNPs for the HSD3B1 gene (rs3765945, rs6203, and rs1047303), and 2 SNPs for the HSD3B2 gene (rs2854964 and rs1819698) was performed. For rs700158 of CYP19A1, the frequencies of the AG+GG genotype and the G allele were significantly higher in PE as compared to controls (P = 0.037, P = 0.033, respectively). Logistic regression analyses indicated that the AG+GG genotype of rs700158 was a PE risk factor (odds ratio = 2.15, P = 0.026). In addition, the frequency of the G-G haplotype established by rs700518-rs4646 was also significantly higher for PE (P = 0.017). These data suggest that the estrogen synthesis gene, CYP19A1 is associated with PE in the Japanese population.

The role of estrogen receptor subtypes for vascular maintenance

Protective role of estrogens (E2) against cardiovascular disease has been appreciated for many years until the equivocal results of cardiovascular outcomes in clinical trials on hormone replacement therapy were reported. Although new ongoing trials aim to resolve these discrepancies, it is obvious that cardiovascular effects of E(2) are complex and diverse. To understand further the cardiovascular effects of E(2), the detailed knowledge on the specific role of both classical estrogen receptor (ER) subtypes and G protein-coupled receptor-30 in the vasculature are of importance. In this article, we review the current knowledge about the pattern of ERalpha and ERbeta expression in human vasculature, the genomic and non-genomic cardiovascular effects of E(2)versus subtype selective ERalpha and ERbeta stimulation on isolated arteries and in different knockout animal models. The results indicate that although ERalpha and ERbeta are expressed in the endothelium and media of human arteries, there is no definite evidence for predominant expression of one over another, the pattern depends on vascular bed, sex and diseased condition. Data from the experiments on isolated arteries and in ER knockout animal models may indicate that activation of specific ER subtypes could provide additional cardiovascular protective effects. However, a clear role for each ERs have to be finalised with focus on mechanisms and by exploring the potential of ERs-selective agonists for clinical utility.