The association of the IVS1-397T>C estrogen receptor α polymorphism with the regulatory conditions in longstanding type 1 diabetic girls

Effect of Estrogen Receptor- Alpha Gene Polymorphism (IVS1-397 T>C) on Microvascular Complications of Type 1 Diabetes Mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is an autoimmune disease whose etiology involves genetic predisposition as well as environmental factors. Polymorphisms of some genes are among the most important genetic factors that influence autoimmunity. Gender is another important factor affecting autoimmunity. Females are more susceptible to autoimmune diseases which may be due to the effect of sex hormones on the immune system activity. The metabolic effects of estrogen are mediated through its receptor - alpha. The exact mechanism is not well understood. A number of polymorphisms have been reported in the Estrogen Receptor- alpha (ER-alpha) IVS1 397 T>C gene which may be involved in the pathogenesis of diabetes.

OBJECTIVES

To assess the influence of Estrogen Receptor- alpha gene [IVS1-397 T>C] polymorphism on vascular complications of type1 diabetes mellitus in pubertal females and on the glycemic control.

METHODS

This cross-sectional case-control study included 40 pubertal regularly menstruating girls less than 18 years with type 1 diabetes mellitus recruited from the Pediatric Diabetes Clinic, Children's Hospital, Ain-Shams University and 20 healthy age-and sex-matched controls. Estrogen receptor alpha genotypes were analyzed by Restriction Fragment Length PCR and correlated with both clinical and laboratory parameters in the studied cases. ER-alpha was chosen as it might play a role in diabetes pathogenesis.

RESULTS

The study revealed the TC genotype was the most prevalent genotype of the estrogen receptor. The TT genotype patients had a younger age of onset of T1DM. The prevalence of obesity was higher among TC and TT than in CC bearing patients. In addition, CC genotype patients had the least prevalence of microalbuminuria and had better glycemic control than other genotypes.

CONCLUSION

Our findings suggest that Estrogen receptor- alpha gene may be affecting the age of onset of Type1 diabetes mellitus in pubertal girls as well as the glycemic control of these patients, where CC bearing girls had better glycemic control than other genotypes and less incidence of microalbuminuria.

Estrogen receptor α gene polymorphism and vascular complications in girls with type 1 diabetes mellitus

The effect of estrogens is mediated by activation of estrogen receptors (ERs). Because ER-α gene polymorphisms may exert different effects in childhood, we analyzed the associations between the IVS1 −397T>C (PvuII) polymorphism and systemic inflammatory state, proangiogenic factors, frequency of monocyte subsets, lipid profile, blood pressure, and vascular complications in girls with type 1 diabetes mellitus (DM1). We examined 180 young girls with DM1 and 120 healthy age-matched controls. The analysis concerned PvuII polymorphism of the ER-α gene as well as the levels of serum inflammatory markers (CRP, IL-6, TNF-α), proangiogenic factors (VEGF, angiogenin), 17β-estradiol, values of monocyte subsets (CD14⁺⁺CD16⁻ and CD14⁺CD16⁺), lipid profile, and blood pressure. In our study, girls with CC genotype had lower level of inflammatory and angiogenic factors and lower frequencies of CD14⁺CD16⁺ monocytes in comparison to CT or TT carriers. Simultaneously, the CC carriers had a greater population of CD14⁺⁺CD16⁻ monocytes, increased blood pressure, and serum levels of: estrogen, total cholesterol, triglycerides, and low-density lipoprotein cholesterol than girls bearing CT or TT genotype. Our study suggests a pleiotropic effect of PvuII polymorphic CC variant on diabetic vasculopathies. Although the CC genotype carriers demonstrate less inflammatory and angiogenic activity, they seem to display less favorable cardiometabolic features. Based on our study, we cannot distinguish PvuII ER-α genotype that could be useful in identification of DM1 girls that are more prone to develop of late vascular complications, before the occurrence of first clinical symptoms.

Genetic Mechanisms Leading to Sex Differences Across Common Diseases and Anthropometric Traits

Common diseases often show sex differences in prevalence, onset, symptomology, treatment, or prognosis. Although studies have been performed to evaluate sex differences at specific SNP associations, this work aims to comprehensively survey a number of complex heritable diseases and anthropometric traits. Potential genetically encoded sex differences we investigated include differential genetic liability thresholds or distributions, gene-sex interaction at autosomal loci, major contribution of the X-chromosome, or gene-environment interactions reflected in genes responsive to androgens or estrogens. Finally, we tested the overlap between sex-differential association with anthropometric traits and disease risk. We utilized complementary approaches of assessing GWAS association enrichment and SNP-based heritability estimation to explore explicit sex differences, as well as enrichment in sex-implicated functional categories. We do not find consistent increased genetic load in the lower-prevalence sex, or a disproportionate role for the X-chromosome in disease risk, despite sex-heterogeneity on the X for several traits. We find that all anthropometric traits show less than complete correlation between the genetic contribution to males and females, and find a convincing example of autosome-wide genome-sex interaction in multiple sclerosis (P = 1 × 10^-9). We also find some evidence for hormone-responsive gene enrichment, and striking evidence of the contribution of sex-differential anthropometric associations to common disease risk, implying that general mechanisms of sexual dimorphism determining secondary sex characteristics have shared effects on disease risk.

Grade of inflammation in boys with type 1 diabetes depends on the IVS1 -397T>C estrogen receptor α polymorphism

BACKGROUND AND AIMS

The effect of estrogens is mediated by activation of estrogen receptors (ERs), which are expressed in many tissues. Because ER-α gene polymorphisms may exert different effects in childhood, in the present study we analyzed associations between the IVS1 -397T>C polymorphism and indicators of inflammatory response as well as late complications in boys with type 1 diabetes mellitus (DM1).

METHODS AND RESULTS

We examined 108 young boys with DM1 and 64 healthy age-matched control individuals. ER-α genotyping, as well as the CRP and IL-6 serum level and blood pressure, was analyzed. In our study boys with CC genotype had lower blood pressure and IL-6 and CRP serum levels. Similar results were obtained for DM1 boys with microvascular complications - the blood pressure and serum level of IL-6, but not CRP, were still lower in the CC patients.

CONCLUSIONS

Our findings suggest that the presence of -397T allele may indicate macro- and microvascular complications in DM1 boys, before the occurrence of first clinical symptoms.

IVS1 -397T>C estrogen receptor α polymorphism is associated with low-grade systemic inflammatory response in type 1 diabetic girls

PURPOSE

The study aimed to investigate the influence of estrogen receptor α (ER-α) genotypes on inflammatory response and development of microvascular complications in girls with type 1 diabetes.

METHODS

152 young regularly menstruating girls with diagnosed type 1 diabetes and 84 young, healthy menstruating girls were recruited. ER-α genotyping was carried out by PCR. Serum concentrations of 17β-estradiol, as well as IL-6, TNF-α, VEGF, and IL-10, were measured. CD4(+)Foxp3(+) TH17 cells were isolated and analyzed by flow cytometry.

RESULTS

Type 1 diabetic girls carrying TT genotype were characterized by the lowest serum estradiol level and IL-10 and highest IL-6, TNF-α, and VEGF. The association between the level of certain cytokine and the genetic variant of estrogen receptor α polymorphism was analyzed. Frequencies of CD4(+)Foxp3(+) TH17 cells were also enhanced in TT bearing girls with type 1 diabetes and correlated with the level of analyzed cytokines. In addition, the correlation between serum estradiol level and cytokine concentrations was observed.

CONCLUSIONS

We propose that TT variant of estrogen receptor α polymorphism may be associated with enhanced inflammatory response, which in turn may lead to acceleration of diabetic retino- and nephropathy in girls with type 1 diabetes. This finding may help the physicians to predict the onset and progression of diabetic microvascular complications.

Association of lymphotoxin alpha polymorphism with type 1 diabetes in a Tunisian population

We investigated the association of the lymphotoxin (LT)-α gene polymorphism +249A/G with type 1 diabetes. The distribution of genotypes of the LT-α +249A/G single nucleotide polymorphism (SNP) was assessed in 115 diabetic patients and 123 normoglycemic control subjects, using PCR-restriction fragment length polymorphism analysis. Among unselected patients, the SNP was significantly associated with increased risk of diabetes (χ2 = 8.44, p = 0.014) and was found to be more pronounced among female (χ2 = 8.37, p = 0.02) than male (χ2 = 6.11, p = 0.047) patients. A significant association was detected between LT-α +249A/G and increased risk of diabetes, in particular for young-onset patients (χ2 = 6.92, p = 0.031). Moreover, we reported significant differences in levels of HbA1c, triglycerides, alanine transaminase, and anti-glutamic acid decarboxylase-65 among alleles. Additional studies with extended patient age groups and different ethnicities are needed to confirm our findings.