Potential advantage of N363S glucocorticoid receptor polymorphism in 21-hydroxylase deficiency

Glucocorticoid receptor Gene (NR3C1) Polymorphisms and Haplotypes in patients with congenital adrenal hyperplasia

BACKGROUND

Lifelong glucocorticoid (GC) replacement is the mainstay treatment of congenital adrenal hyperplasia (CAH) due to classic 21-hydroxylase deficiency (21-OHD). Challenges posed by therapeutic management of these patients are well known, but novel insights into the variability in clinical response to GC highlight a role for single nucleotide polymorphisms (SNPs) of the glucocorticoid receptor gene (NR3C1).

AIM

To assess whether six commonly studied NR3C1 SNPs, which were previously associated with modified response to GC, are associated with CAH. We further assessed the linkage disequilibrium (LD) among these NR3C1 SNPs and their combination into haplotypes.

METHODS

Genotypes were determined by Taqman allele discrimination assays for Tth111I (rs10052957), ER22 (rs6189), 23 EK (rs6190), N363S (rs56149945), BclI (rs41423247) and 9β (rs6198) in a Brazilian cohort of 102 unrelated 21-OHD patients and 163 unrelated healthy subjects (controls). Haplotypes were estimated using Haplo.stats, and LD among SNPs using Haploview.

RESULTS

Heterozygous subjects for Tth111I were more frequent in 21-OHD patients (P = 0.004), while heterozygous for BclI were more frequent in controls (P = 0.049). We found a strong LD among the six NR3C1 SNPs, and four out of six common haplotypes contained the Tth111I-variant. Although we found no significant differences in overall haplotype analysis, the BclI-haplotype was less frequent among 21-OHD patients (P = 0.0180).

CONCLUSIONS

BclI-haplotype was less common and heterozygous for Tth111I were more frequent in 21-OHD patients, while heterozygous for BclI were more frequent in controls. Our novel findings may contribute to further clinical studies on the prognostic value of NR3C1 haplotypes towards individualized treatment for 21-OHD patients.

Generalized and tissue specific glucocorticoid resistance

Glucocorticoids (GCs) are steroid hormones that influence several physiologic functions and are among the most frequently prescribed drugs worldwide. Resistance to GCs has been observed in the context of the familial generalized GC resistance (Chrousos' syndrome) or tissue specific GC resistance in chronic inflammatory states. In this review, we have summarized the major factors that influence individual glucocorticoid sensitivity/resistance. The fine-tuning of GC action is determined in a tissue-specific fashion that includes the combination of different GC receptor promoters, translation initiation sites, splice isoforms, interacting proteins, post-translational modifications, and alternative mechanisms of signal transduction.

Nonvirilized Genitalia in 3 Female Newborns With the Salt-Wasting Congenital Adrenal Hyperplasia Phenotype

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, a form of primary adrenal insufficiency characterized by impaired cortisol secretion and elevated androgen production, is the leading cause of atypical genitalia in the female newborn. Females with classic CAH, either salt-wasting or simple-virilizing form, usually present at birth with atypical genitalia ranging from clitoromegaly to male-appearing genitalia, due to in utero to elevated androgens (androstenedione and testosterone). Females with mild nonclassic CAH usually present with typical genitalia. Proving the importance of always keeping an open mind for exceptions to the rule, we report on 3 female newborns who presented with the nonvirilized genitalia, salt-wasting CAH phenotype and genotype most consistent with simple-virilizing CAH. It is only through a positive newborn screen identifying the females with CAH that they were diagnosed before developing adrenal and/or salt-wasting crisis.

A unique haplotype of RCCX copy number variation: from the clinics of congenital adrenal hyperplasia to evolutionary genetics

There is a difficulty in the molecular diagnosis of congenital adrenal hyperplasia (CAH) due to the c.955C>T (p.(Q319*), formerly Q318X, rs7755898) variant of the CYP21A2 gene. Therefore, a systematic assessment of the genetic and evolutionary relationships between c.955C>T, CYP21A2 haplotypes and the RCCX copy number variation (CNV) structures, which harbor CYP21A2, was performed. In total, 389 unrelated Hungarian individuals with European ancestry (164 healthy subjects, 125 patients with non-functioning adrenal incidentaloma and 100 patients with classical CAH) as well as 34 adrenocortical tumor specimens were studied using a set of experimental and bioinformatic methods. A unique, moderately frequent (2%) haplotypic RCCX CNV structure with three repeated segments, abbreviated to LBSASB, harboring a CYP21A2 with a c.955C>T variant in the 3'-segment, and a second CYP21A2 with a specific c.*12C>T (rs150697472) variant in the middle segment occurred in all c.955C>T carriers with normal steroid levels. The second CYP21A2 was free of CAH-causing mutations and produced mRNA in the adrenal gland, confirming its functionality and ability to rescue the carriers from CAH. Neither LBSASB nor c.*12C>T occurred in classical CAH patients. However, CAH-causing CYP21A2 haplotypes with c.955C>T could be derived from the 3'-segment of LBSASB after the loss of functional CYP21A2 from the middle segment. The c.*12C>T indicated a functional CYP21A2 and could distinguish between non-pathogenic and pathogenic genomic contexts of the c.955C>T variant in the studied European population. Therefore, c.*12C>T may be suitable as a marker to avoid this genetic confound and improve the diagnosis of CAH.

Glucocorticoid receptor gene polymorphisms in hereditary angioedema with C1-inhibitor deficiency

BACKGROUND

Hereditary angioedema caused by C1-inhibitor deficiency (C1-INH-HAE) is a rare, autosomal dominant disorder. C1-INH-HAE is characterized by edema-formation, which may occur in response to stress. The individual's response to stress stimuli is partly genetically determined. Activation of the hypothalamic-pituitary-adrenal axis results in the release of cortisol. In turn, the secreted gluco- and mineralocorticoids affect the metabolism, as well as the cardiovascular and immune systems. We hypothesized that changes in serum cortisol level and polymorphisms of the glucocorticoid receptor (GR) modify the individual sensitivity to stressor stimuli of C1-INH-HAE patients.

RESULTS

We compared the response to stress with Rahe's Brief Stress and Coping Inventory of 43 C1-INH-HAE patients, 18 angioedema patients and 13 healthy controls. 139 C1-INH-HAE patients and 160 healthy controls were genotyped for glucocorticoid receptor polymorphisms BclI, N363S and A3669G. Serum cortisol levels were determined during attacks and during symptom-free periods in 36 C1-INH-HAE patients. The relationships between clinical, laboratory data and GR SNPs (Single Nucleotide Polymorphisms) were assessed using ANOVA. C1-INH-HAE patients have decreased coping capabilities compared to healthy controls. Cortisol levels were significantly higher during attacks than in symptom-free periods (p = 0.004). The magnitude of the elevation of cortisol levels did not show a significant correlation with any clinical or laboratory data. Among the C1-INH-HAE patients, the carriers of the A3669G allele had significantly lower cortisol levels, and increased body mass index compared with non-carriers.

CONCLUSIONS

The higher cortisol level observed during attacks may reflect the effect of a stressful situation (such as of the attack itself), on the patients' neuroendocrine system. In A3669G carriers, the lower cortisol levels might reflect altered feedback to the hypothalamic-pituitary-adrenal axis, due to decreased sensitivity to glucocorticoids.

Polymorphisms of the GR and HSD11B1 genes influence body mass index and weight gain during hormone replacement treatment in patients with Addison's disease

OBJECTIVE

Glucocorticoid substitution is essential in patients with chronic primary adrenocortical insufficiency (Addison's disease) and both over-treatment and inadequate dosage have deleterious effects. Individual sensitivity to glucocorticoids is partly genetically determined.

CONTEXT

To test the hypothesis whether the well-characterized SNPs of the GR and HSD11B1 genes may modulate the individual sensitivity to exogenous glucocorticoids and may influence clinical and/or laboratory parameters and the glucocorticoid substitution dosage in patients with Addison's disease.

PATIENTS AND METHODS

68 patients with primary adrenocortical insufficiency were involved. Clinical and laboratory data, as well as the dosage of the hormone replacement therapy were collected. Peripheral blood DNA was isolated, and the GR and HSD11B1 SNPs were examined using allele-specific PCR or Taqman assay on Real Time PCR.

RESULTS

The allele frequency of the GR N363S polymorphism was higher in patients compared to the control group and the disease appeared significantly earlier in patients harbouring the GR A3669G compared to noncarriers. These patients had higher ACTH level measured at the time of diagnosis. Homozygous BclI carriers had higher body mass index (BMI) and lower total hydrocortisone equivalent supplementation dose needed than heterozygous or noncarriers. The BMI and weight gain during hormone replacement therapy were also higher in carriers of the HSD11B1 rs4844880 treated with glucocorticoids other than dexamethasone.

CONCLUSION

The BclI polymorphism of the GR gene and the rs4844880 of the HSD11B1 gene may contribute to weight gain and may affect the individual need of glucocorticoid substitution dose in these patients.

Glucocorticoid receptor polymorphisms and haplotypes and their expression in health and disease

Cortisol is involved in many physiological processes, including immunosuppressive and anti-inflammatory actions, and therefore cortisol and its synthetic analogs are widely used to treat a large number of diseases. In glucocorticoid treatment, a large variability of clinical responses is observed. This variability may, in part, be ascribed to genetic variation in the glucocorticoid receptor (GR) gene. In this review we present a catalogue of the various single nucleotide polymorphisms (SNPs) in the glucocorticoid receptor gene and their consequences for human health and disease. Many different GR SNP association studies have been described. However, most studies come down to only a few SNPs reported with different annotations. In this review we clarified these different annotations to uniform names. Most associations between GR SNPs and phenotype have been found in body composition, metabolism, the cardiovascular system, the immune system and psychiatric illnesses. However, many associations have not been replicated (yet), and future replication studies and meta-analyses are needed. There is a substantial body of evidence for GR SNPs to have effects on clinical phenotype. However, as most SNP frequencies are low and their variation is within the range of the general population, the impact of a single SNP for health and disease in the general population is probably modest. However, in-depth studying of the molecular mechanisms of repeatedly observed clinical associations could lead to new possibilities for drug development. In particular the development of selective glucocorticoid receptor modulators holds promise.

BClI polymorphism of the glucocorticoid receptor gene is associated with increased obesity, impaired glucose metabolism and dyslipidaemia in patients with Addison's disease

OBJECT

Although glucocorticoids are essential for health, several studies have shown that glucocorticoids replacement in Addison's disease might be involved in anthropometric and metabolic impairment, with increased cardiovascular risk, namely if conventional doses are used. As the effects of glucocorticoids are mediated by the glucocorticoid receptor, encoded by NR3C1 gene, different polymorphisms in the NR3C1 gene have been linked to altered glucocorticoid sensitivity in general population as well as in patients with obesity or metabolic syndrome.

DESIGN

We investigated the impact of glucocorticoid receptor gene polymorphisms, including the BclI, N363S and ER22/23EK variants, on anthropometric parameters (BMI and waist circumference), metabolic profile (HOMA, OGTT and serum lipids) and ACTH levels in 50 patients with Addison's disease (34 women and 16 men, age 20-82 year) under glucocorticoids replacement.

RESULTS

Neither N363S nor ER22/23EK variants were significantly associated with anthropometric, metabolic or hormonal parameters, while patients carrying the homozygous BclI polymorphism GG (n = 4) showed higher (P < 0·05) BMI, waist circumference, HOMA and 2-h glucose levels after OGTT, as well as total cholesterol and triglycerides than those with wild-type genotype CC (n = 28) or heterozygous CG (n = 18). The totality of GG patients was connoted by abdominal adiposity, impaired glucose tolerance/diabetes mellitus or dyslipidaemia, while a lower percentage of CC or CG patients showed some anthropometric and metabolic alterations.

CONCLUSION

These results suggest that BclI polymorphism may influence the sensitivity to glucocorticoids in patients with Addison's disease and may contribute, along with other factors, to the increase in central adiposity, impaired glucose metabolism and dyslipidaemia.

Clinical features associated with glucocorticoid receptor polymorphisms. An overview

The glucocorticoid receptor (GR) is crucial for the effects of glucocorticoids (GCs). Several polymorphisms of the GR are associated with altered sensitivity to GCs. For the ER22/23EK polymorphism, a relative GC resistance has been demonstrated. In vivo, this was suggested by a smaller response to a dexamethasone suppression test (DST), whereas in vitro experiments showed a diminished transactivational activity. The associated features of ER22/23EK carriers consist of favorable metabolic and body compositional conditions. In elderly subjects this polymorphism was associated with longevity and decreased risk of dementia. Interestingly, recent studies also showed an increased risk of major depression. In contrast, the N363S polymorphism was reported to be associated with an enhanced sensitivity to GCs, as was demonstrated by a DST. This polymorphism has also been associated with increased body mass index (BMI) and LDL-cholesterol levels, as well as increased risk of cardiovascular disease. However, additional studies yielded conflicting results, showing no associations with being overweight. The BclI polymorphism is also associated with increased GC sensitivity. In addition, associations with increased abdominal fat mass, Crohn's disease and, remarkably, major depression have been reported. Another GR polymorphism, located in exon 9beta, is associated with increased expression and stabilization of the dominant negative splice variant GR-beta. Carriers of this polymorphism displayed a relative GC resistance in vitro as evidenced by diminished transrepressional activity, which is important for the immune system and inflammation. Associations have been found with increased inflammatory parameters, cardiovascular disease, and rheumatoid arthritis. In this article, studies concerning these clinically relevant GR variants are discussed.

The protective effect of the ER22/23EK polymorphism against an excessive weight gain during pregnancy

It has been shown that women who gained an excessive weight during pregnancy had an increase in long-term BMI compared with those without an excessive weight gain. Several studies have demonstrated that some polymorphisms of the glucocorticoid receptor (GR) gene may influence body composition and metabolic parameters. In the present study, we wanted to explore whether any association could exist between the BclI, N363S and ER22/23EK polymorphisms of the GR gene and the weight gain during pregnancy. We found that the allelic frequencies of the BclI, N363S and ER22/23EK polymorphisms in 300 women with uncomplicated pregnancies were similar to those measured in healthy Hungarian population. None of the three polymorphisms associated with body weight or BMI at the 1st trimester of pregnancy or before delivery. However, a significantly lower weight gain (p = 0.044) and consequently lower increase of BMI during pregnancy (p = 0.044) was observed in heterozygous carriers of the ER22/23EK polymorphism. These results support a protective role of the ER22/23EK polymorphism against an excessive weight gain and excessive increase of BMI during uncomplicated pregnancy.

Functional glucocorticoid receptor gene variants do not underlie the high variability of 17-hydroxyprogesterone screening values in healthy newborns

OBJECTIVE

17-Hydroxyprogesterone (17-OHP) screening for classical congenital adrenal hyperplasia (CAH) is part of many newborn screening programs worldwide. Cut-off values are relatively high, and screening sensitivity does not reach 100%. Recently, the glucocorticoid receptor (GR) N363S-variant has been linked to relatively low degree of virilization and comparatively lower 17-OHP serum concentrations in clinically diagnosed female CAH patients. We sought to determine whether functional GR gene variants, either increasing (N363S, BclI) or decreasing GR sensitivity (R23K), underlie the variable 17-OHP screening levels in healthy newborns.

DESIGN

GR genotypes were compared with 17-OHP screening values in 1000 random samples from routine screening. 17-OHP was measured by conventional immunoassay (TRFIA) and a liquid chromatography-tandem mass spectrometry method (LC-MS/MS), which has been shown to increase screening specificity by steroid profiling and avoiding cross-reactions of the 17-OHP-antibody.

RESULTS

There was no significant association of 17-OHP with GR genotypes, even after inclusion of gestational and postnatal age as covariates. However, among LC-MS/MS steroid measurements, we observed some unexpected trends, including lower 11-deoxycortisol concentrations in both 363S- and 23K-carriers. For carriers of the frequent BclI variant, linear regression analysis revealed a significant increase of 4-androstenedione levels with every mutant allele inherited.

CONCLUSIONS

Functional GR variants do not underlie the variation of 17-OHP values observed in healthy individuals. However, whether and to which extent genetically determined differences in individual GR sensitivity influence 17-OHP screening levels in conditions of a pathological hypothalamus-pituitary-adrenal gland-axis stimulation and thus may explain false-negative screening results in those affected by CAH remains to be investigated.

Association between birth weight in preterm neonates and the BclI polymorphism of the glucocorticoid receptor gene

Endogenous and exogenous glucocorticoids influence fetal growth and development, and maternal administration of synthetic glucocorticoids may decrease the risk of perinatal morbidity including lung disease in preterm neonates. Because polymorphisms of the glucocorticoid receptor gene are known to influence the sensitivity to glucocorticoids, in the present study we examined whether any associations could exist among the BclI, N363S and ER22/23EK polymorphisms of the glucocorticoid receptor gene and gestational age, birth weight and/or perinatal morbidity of 125 preterm neonates born at 28-35 weeks' gestation with (n=57) or without maternal dexamethasone treatment (n=68). The prevalence of the three polymorphisms in the whole group of preterm infants was similar to that reported in healthy adult Hungarian population. However, we found that the BclI polymorphism significantly associated with higher birth weight adjusted for the gestational age (p=0.004, ANOVA analysis). None of the three polymorphisms showed an association with perinatal morbidities, including necrotizing enterocolitis, intraventricular hemorrhagia, patent ductus arteriosus, respiratory distress syndrome, bronchopulmonary dysplasia and sepsis in the two groups of preterm neonates with and without maternal dexamethasone treatment. These results suggest that the BclI polymorphism of the glucocorticoid receptor gene may have an impact on gestational age-adjusted birth weight, but it does not influence perinatal morbidities of preterm neonates.

Association of the GAA1013→GAG polymorphism of the insulin-like growth factor-1 receptor (IGF1R) gene with premature pubarche

OBJECTIVE

A single-nucleotide polymorphism (SNP), the G variant in codon 1013 (GAA1013-->GAG) of the insulin-like growth factor-1 (IGF-1) receptor (IGFIR) gene, has been associated with higher IGF-1 concentrations in Caucasian subjects. Because elevated serum levels of IGF-1 have been described in children with premature pubarche (PP) and in adolescent girls with hyperandrogenism, we tested the a priori hypothesis that the frequency of the A-->G variant would be overrepresented among children with PP.

DESIGN

Case-control association study.

SETTING

University-based pediatric endocrinology practice.

PATIENT(S)

Sixty-nine children (63 girls and 6 boys) with PP, 52 adolescent girls with hyperandrogenism, and 92 healthy subjects.

INTERVENTION(S)

Blood was obtained for genotype analysis, glucose measurement, and hormone (A, insulin, 17-hydroxyprogesterone, and T) determinations.

MAIN OUTCOME MEASURE(S)

Frequency of the SNP in the IGF1R gene and correlation of this SNP with hormone concentrations.

RESULT(S)

Distribution of the G allele was statistically significantly different between the children with PP and the healthy control subjects, independent of insulin sensitivity.

CONCLUSION(S)

This common SNP in the IGF1R gene may be associated with PP caused by premature adrenarche in children. Because PP has been associated with higher IGF-1 concentrations, these data suggest a potential molecular basis for prior clinical observations of elevated IGF-1 concentrations in children with PP.