Baxdrostat: A Novel Aldosterone Synthase Inhibitor for Treatment Resistant Hypertension.

Hypertension is a global epidemic, affecting around 30.4% of the population and being the leading preventable risk factor for death. Despite the availability of numerous antihypertensive agents, less than 20% of individuals have their blood pressure controlled. Resistant hypertension poses a challenge, but a new class of medication, aldosterone synthase inhibitors (ASI), shows promise. ASI reduces aldosterone production by inhibiting aldosterone synthase. This review article focuses on Baxdrostat, a highly potent ASI currently in phase 3 trials. It discusses the drug's biochemical pathway, efficacy trials in animals and humans, and its potential in uncontrolled hypertension, chronic kidney disease, and primary aldosteronism.

Pathogenesis of Primary Aldosteronism: Impact on Clinical Outcome.

Primary aldosteronism (PA) is the most common form of secondary arterial hypertension, with a prevalence of approximately 20% in patients with resistant hypertension. In the last decade, somatic pathogenic variants in KCNJ5, CACNA1D, ATP1A1 and ATP2B3 genes, which are involved in maintaining intracellular ionic homeostasis and cell membrane potential, were described in aldosterone-producing adenomas (aldosteronomas). All variants in these genes lead to the activation of calcium signaling, the major trigger for aldosterone production. Genetic causes of familial hyperaldosteronism have been expanded through the report of germline pathogenic variants in KCNJ5, CACNA1H and CLCN2 genes. Moreover, PDE2A and PDE3B variants were associated with bilateral PA and increased the spectrum of genetic etiologies of PA. Of great importance, the genetic investigation of adrenal lesions guided by the CYP11B2 staining strongly changed the landscape of somatic genetic findings of PA. Furthermore, CYP11B2 staining allowed the better characterization of the aldosterone-producing adrenal lesions in unilateral PA. Aldosterone production may occur from multiple sources, such as solitary aldosteronoma or aldosterone-producing nodule (classical histopathology) or clusters of autonomous aldosterone-producing cells without apparent neoplasia denominated aldosterone-producing micronodules (non-classical histopathology). Interestingly, KCNJ5 mutational status and classical histopathology of unilateral PA (aldosteronoma) have emerged as relevant predictors of clinical and biochemical outcome, respectively. In this review, we summarize the most recent advances in the pathogenesis of PA and discuss their impact on clinical outcome.

Classic and current concepts in adrenal steroidogenesis: a reappraisal.

Adrenal steroid biosynthesis and its related pathology are constant evolving disciplines. In this paper, we review classic and current concepts of adrenal steroidogenesis, plus control mechanisms of steroid pathways, distribution of unique enzymes and cofactors, and major steroid families. We highlight the presence of a "mineralocorticoid (MC) pathway of zona fasciculata (ZF)", where most circulating corticosterone and deoxycorticosterone (DOC) originate together with 18OHDOC, under ACTH control, a claim based on functional studies in normal subjects and in patients with 11ß-, and 17α-hydroxylase deficiencies. We emphasize key differences between CYP11B1 (11ß-hydroxylase) and CYP11B2 (aldosterone synthase) and the onset of a hybrid enzyme - CYP11B1/CYP11B2 -, responsible for aldosterone formation in ZF under ACTH control, in "type I familial hyperaldosteronism" (dexamethasone suppressible). In "apparent MC excess syndrome", peripheral conversion of cortisol to cortisone is impaired by lack of 11ß-hydroxysteroid dehydrogenase type 2, permitting free cortisol access to MC receptors resulting in severe hypertension. We discuss two novel conditions involving the synthesis of adrenal androgens: the "backdoor pathway", through which dihydrotestosterone is formed directly from androsterone, being relevant for the fetoplacental setting and sexual differentiation of male fetuses, and the rediscovery of C19 11-oxygenated steroids (11-hydroxyandrostenedione and 11-ketotestosterone), active androgens and important markers of virilization in 21-hydroxylase deficiency and polycystic ovaries syndrome. Finally, we underline two enzyme cofactor deficiencies: cytochrome P450 oxidoreductase which partially affects 21- and 17α-hydroxylation, producing a combined clinical/hormonal picture and causing typical skeletal malformations (Antley-Bixler syndrome), and PAPSS2, coupled to SULT2A1, that promotes sulfation of DHEA to DHEAS, preventing active androgens to accumulate. Its deficiency results in reduced DHEAS and elevated DHEA and androgens with virilization. Future and necessary studies will shed light on remaining issues and questions on adrenal steroidogenesis.

Classic and current concepts in adrenal steroidogenesis: a reappraisal

ABSTRACT Adrenal steroid biosynthesis and its related pathology are constant evolving disciplines. In this paper, we review classic and current concepts of adrenal steroidogenesis, plus control mechanisms of steroid pathways, distribution of unique enzymes and cofactors, and major steroid families. We highlight the presence of a "mineralocorticoid (MC) pathway of zona fasciculata (ZF)", where most circulating corticosterone and deoxycorticosterone (DOC) originate together with 18OHDOC, under ACTH control, a claim based on functional studies in normal subjects and in patients with 11β-, and 17α-hydroxylase deficiencies. We emphasize key differences between CYP11B1 (11β-hydroxylase) and CYP11B2 (aldosterone synthase) and the onset of a hybrid enzyme - CYP11B1/CYP11B2 -, responsible for aldosterone formation in ZF under ACTH control, in "type I familial hyperaldosteronism" (dexamethasone suppressible). In "apparent MC excess syndrome", peripheral conversion of cortisol to cortisone is impaired by lack of 11β-hydroxysteroid dehydrogenase type 2, permitting free cortisol access to MC receptors resulting in severe hypertension. We discuss two novel conditions involving the synthesis of adrenal androgens: the "backdoor pathway", through which dihydrotestosterone is formed directly from androsterone, being relevant for the fetoplacental setting and sexual differentiation of male fetuses, and the rediscovery of C19 11-oxygenated steroids (11-hydroxyandrostenedione and 11-ketotestosterone), active androgens and important markers of virilization in 21-hydroxylase deficiency and polycystic ovaries syndrome. Finally, we underline two enzyme cofactor deficiencies: cytochrome P450 oxidoreductase which partially affects 21- and 17α-hydroxylation, producing a combined clinical/hormonal picture and causing typical skeletal malformations (Antley-Bixler syndrome), and PAPSS2, coupled to SULT2A1, that promotes sulfation of DHEA to DHEAS, preventing active androgens to accumulate. Its deficiency results in reduced DHEAS and elevated DHEA and androgens with virilization. Future and necessary studies will shed light on remaining issues and questions on adrenal steroidogenesis.

Testosterona inhibe la actividad de la aldosterona sintasa silvestre y quimérica in vitro / Testosterone inhibits human wild-type and chimeric aldosterone synthase activity in vitro

BACKGROUND: Familial hyperaldosteronism type I is caused by the generation of a chimeric aldosterone synthase enzyme (ASCE) which is regulated by ACTH instead of angiotensin II. We have reported that in vitro, the wild-type (ASWT) and chimeric aldosterone synthase (ASCE) enzymes are inhibited by progesterone and estradiol does not affect their activity. AIM: To explore the direct action of testosterone on ASWT and ASCE enzymes. Material and Methods: HEK-293 cells were transiently transfected with vectors containing the full ASWT or ASCE cDNAs. The effect of testosterone on AS enzyme activities was evaluated incubating HEK-cells transfected with enzyme vectors and adding deoxycorticosterone (DOC) alone or DOC plus increasing doses of testosterone. Aldosterone production was measured by HPLC-MS/MS. Docking of testosterone within the active sites of both enzymes was performed by modelling in silico. Results: In this system, testosterone inhibited ASWT (90% inhibition at five pM, 50% inhibitory concentration (IC50) =1.690 pM) with higher efficacy andpotency than ASCE (80% inhibition at five pM, IC50=3.176 pM). Molecular modelling studies showed different orientation of testosterone in ASWT and ASCE crystal structures. CONCLUSIONS: The inhibitory effect of testosterone on ASWT or ASCE enzymes is a novel non-genomic testosterone action, suggesting that further clinical studies are needed to assess the role of testosterone in the screening and diagnosis of primary aldosteronism.

[Testosterone inhibits human wild-type and chimeric aldosterone synthase activity in vitro]. / Testosterona inhibe la actividad de la aldosterona sintasa silvestre y quimérica in vitro.

BACKGROUND: Familial hyperaldosteronism type I is caused by the generation of a chimeric aldosterone synthase enzyme (ASCE) which is regulated by ACTH instead of angiotensin II. We have reported that in vitro, the wild-type (ASWT) and chimeric aldosterone synthase (ASCE) enzymes are inhibited by progesterone and estradiol does not affect their activity. AIM: To explore the direct action of testosterone on ASWT and ASCE enzymes. MATERIAL AND METHODS: HEK-293 cells were transiently transfected with vectors containing the full ASWT or ASCE cDNAs. The effect of testosterone on AS enzyme activities was evaluated incubating HEK-cells transfected with enzyme vectors and adding deoxycorticosterone (DOC) alone or DOC plus increasing doses of testosterone. Aldosterone production was measured by HPLC-MS/MS. Docking of testosterone within the active sites of both enzymes was performed by modelling in silico. RESULTS: In this system, testosterone inhibited ASWT (90% inhibition at five pM, 50% inhibitory concentration (IC50) =1.690 pM) with higher efficacy andpotency than ASCE (80% inhibition at five pM, IC50=3.176 pM). Molecular modelling studies showed different orientation of testosterone in ASWT and ASCE crystal structures. CONCLUSIONS: The inhibitory effect of testosterone on ASWT or ASCE enzymes is a novel non-genomic testosterone action, suggesting that further clinical studies are needed to assess the role of testosterone in the screening and diagnosis of primary aldosteronism.

Contribution of rs1799998 polymorphism in CYP11B2 gene in susceptibility to preeclampsia / Contribuição do polimorfismo rs1799998 no gene CYP11B2 na suscetibilidade à pré-eclampsia

Abstract Objectives: the present study aimed to evaluate the association between the rs1799998 polymorphism of the CYP11B2 gene and the susceptibility to preeclampsia (PE) in a Brazilian population. Methods: the study group comprised 61 women who were diagnosed with PE. The control group included 116 women who did not show changes in their blood pressure levels during their pregnancies. The rs1799998 polymorphism of the CYP11B2 gene was amplified by allele-specific polymerase chain reaction (PCR). A multiple logistic regression analysis was performed using the SNPStat program to evaluate the risk of the CYP11B2 gene rs1799998 polymorphism contributing to PE. Results: the PE group had the following genotypes: 1.64% CC, 91.80% CT, and 6.56% TT. In the control group, the observed genotypic frequencies were: 11% CC, 73% CT, and 16% TT. The genotypic frequency distribution did not fit the Hardy Weinberg Equilibrium (HWE) in either study group. The multiple logistic regression analysis showed a statistically significant difference for the rs1799998 polymorphism in the recessive model. Conclusion: the results suggest an association between the recessive model of C/C genotype of the rs1799998 polymorphism of the CYP11B2 gene and susceptibility to PE.

Resumo Objetivos: avaliar a associação entre o polimorfismo rs1799998 do gene CYP11B2 e a suscetibilidade à PE em uma população brasileira. Métodos: participaram desse estudo 61 mulheres com PE e 116 mulheres normotensas. O polimorfismo rs1799998 do gene CYP11B2 foi amplificado por PCR alelo-específica. O risco do polimorfismo rs1799998 do gene CYP11B2 contribuir com a PE foi avaliado pela análise de regressão logística múltipla. Resultados: as frequências genotípicas observadas foram 1.64% CC, 91.80% CT e 6.56% TT no grupo PE e 11%CC, 73%CT e 16%TT grupo controle. A distribuição da frequência genotípica não estava em Equilíbrio de Hardy Weinberg em nenhum dos grupos estudados. A análise de regressão logística múltipla demonstrou diferença estatisticamente significativa para o polimorfismo rs1799998 no modelo recessivo. Conclusão: o presente trabalho sugere associação do genótipo C/C no modelo recessivo, do polimorfismo rs1799998 do gene CYP11B2 com a suscetibilidade a PE.

Congenital hyperreninemic hypoaldosteronism due to aldosterone synthase deficiency type I in a Portuguese patient - Case report and review of literature.

Hyperreninemic hypoaldosteronism due to aldosterone synthase (AS) deficiency is a rare condition typically presenting as salt-wasting syndrome in the neonatal period. A one-month-old Portuguese boy born to non-consanguineous parents was examined for feeding difficulties and poor weight gain. A laboratory workup revealed severe hyponatremia, hyperkaliaemia and high plasma renin with unappropriated normal plasma aldosterone levels, raising the suspicion of AS deficiency. Genetic analysis showed double homozygous of two different mutations in the CYP11B2 gene: p.Glu198Asp in exon 3 and p.Val386Ala in exon 7. The patient maintains regular follow-up visits in endocrinology clinics and has demonstrated a favourable clinical and laboratory response to mineralocorticoid therapy. To our knowledge, this is the first Portuguese case of AS deficiency reported with confirmed genetic analysis.

Congenital hyperreninemic hypoaldosteronism due to aldosterone synthase deficiency type I in a Portuguese patient - Case report and review of literature

SUMMARY Hyperreninemic hypoaldosteronism due to aldosterone synthase (AS) deficiency is a rare condition typically presenting as salt-wasting syndrome in the neonatal period. A one-month-old Portuguese boy born to non-consanguineous parents was examined for feeding difficulties and poor weight gain. A laboratory workup revealed severe hyponatremia, hyperkaliaemia and high plasma renin with unappropriated normal plasma aldosterone levels, raising the suspicion of AS deficiency. Genetic analysis showed double homozygous of two different mutations in the CYP11B2 gene: p.Glu198Asp in exon 3 and p.Val386Ala in exon 7. The patient maintains regular follow-up visits in endocrinology clinics and has demonstrated a favourable clinical and laboratory response to mineralocorticoid therapy. To our knowledge, this is the first Portuguese case of AS deficiency reported with confirmed genetic analysis.

Association between the CYP11B2 gene -344T>C polymorphism and coronary artery disease: a meta-analysis.

Numerous studies have evaluated the association between the CYP11B2 gene -344T>C polymorphism and coronary artery disease (CAD) risk. However, the specific association is still controversial. To address this issue, PubMed, EMBASE, and China National Knowledge Infrastructure databases were searched for eligible articles that reported on the relationship between the CYP11B2 gene -344T>C polymorphism and CAD, and were published before April 2014. Data from five separate studies with 3687 subjects were analyzed by meta-analysis. No significant variation in CAD risk was detected by any of the genetic models in the overall study population. Taking into account the effect of ethnicity, further stratified analyses demonstrated significant association in both Caucasian (TT vs TC: OR = 0.80, 95%CI = 0.64-1.00) and Asian populations (TT vs TC: OR = 1.25, 95%CI = 1.01-1.54; dominant model: OR = 0.80, 95%CI = 0.66-0.98). The pooled ORs were not substantially altered after the exclusion of one study in the control group that deviated from Hardy-Weinberg equilibrium, highlighting the reliability of our meta-analysis results. In conclusion, this meta-analysis suggested that the -344T>C polymorphism in the CYP11B2 gene might be associated with susceptibility to CAD in Caucasians and Asians.

Changes in cardiac aldosterone and its synthase in rats with chronic heart failure: an intervention study of long-term treatment with recombinant human brain natriuretic peptide.

The physiological mechanisms involved in isoproterenol (ISO)-induced chronic heart failure (CHF) are not fully understood. In this study, we investigated local changes in cardiac aldosterone and its synthase in rats with ISO-induced CHF, and evaluated the effects of treatment with recombinant human brain natriuretic peptide (rhBNP). Sprague-Dawley rats were divided into 4 different groups. Fifty rats received subcutaneous ISO injections to induce CHF and the control group (n=10) received equal volumes of saline. After establishing the rat model, 9 CHF rats received no further treatment, rats in the low-dose group (n=8) received 22.5 µg/kg rhBNP and those in the high-dose group (n=8) received 45 µg/kg rhBNP daily for 1 month. Cardiac function was assessed by echocardiographic and hemodynamic analysis. Collagen volume fraction (CVF) was determined. Plasma and myocardial aldosterone concentrations were determined using radioimmunoassay. Myocardial aldosterone synthase (CYP11B2) was detected by quantitative real-time PCR. Cardiac function was significantly lower in the CHF group than in the control group (P<0.01), whereas CVF, plasma and myocardial aldosterone, and CYP11B2 transcription were significantly higher than in the control group (P<0.05). Low and high doses of rhBNP significantly improved hemodynamics (P<0.01) and cardiac function (P<0.05) and reduced CVF, plasma and myocardial aldosterone, and CYP11B2 transcription (P<0.05). There were no significant differences between the rhBNP dose groups (P>0.05). Elevated cardiac aldosterone and upregulation of aldosterone synthase expression were detected in rats with ISO-induced CHF. Administration of rhBNP improved hemodynamics and ventricular remodeling and reduced myocardial fibrosis, possibly by downregulating CYP11B2 transcription and reducing myocardial aldosterone synthesis.

Aldosterone synthase gene polymorphism and renal histopathologic changes in kidney transplant patients receiving a calcineurin inhibitor.

INTRODUCTION: Aldosterone participates in the pathogenesis of calcineurin inhibitor nephrotoxicity (CIN), producing renal vasoconstriction and transforming growth factor beta (TGFß) expression. The objective of this study was to assess aldosterone polymorphisms and relationships to plasma aldosterone levels and the development of renal histological lesions in kidney transplant patients. MATERIAL AND METHODS: Patients with kidney graft biopsy were divided according to the presence or absence of CIN. We determined aldosterone synthase (AS) -344 T/C and int 2 W/C gene polymorphisms and plasma aldosterone levels. Histological, biochemical and clinical variables were measured. RESULTS: Calcineurin inhibitor (CI) levels were significantly higher in patients with the int 2 WW genotype than in patients with WC or CC genotypes. There was a greater degree of interstitial fibrosis in patients with int 2 CC genotype. No relationship was found between the different polymorphisms and a higher degree and/or frequency of CIN. There was also no relationship with plasma aldosterone levels. CONCLUSION: The frequency of the different polymorphisms studied was not related to plasma aldosterone levels or the development of CIN; however, the int 2 CC genotype was related to a greater degree of interstitial fibrosis, whereas the WW genotype was related to higher CI serum levels.

Different effects of progesterone and estradiol on chimeric and wild type aldosterone synthase in vitro.

BACKGROUND: Familial hyperaldosteronism type I (FH-I) is caused by the unequal recombination between the 11beta-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes, resulting in the generation of a CYP11B1/B2 chimeric gene and abnormal adrenal aldosterone production. Affected patients usually show severe hypertension and an elevated frequency of stroke at a young age. Aldosterone levels rise during pregnancy, yet in pregnant women with FH-1, their hypertensive condition either remains unchanged or may even improve. The purpose of this study was to investigate in vitro whether female sex steroids modulate the activity of chimeric (ASCE) or wild type (ASWT) aldosterone synthase enzymes. METHODS: We designed an in vitro assay using HEK-293 cell line transiently transfected with vectors containing the full ASCE or ASWT cDNAs. Progesterone or estradiol effects on AS enzyme activities were evaluated in transfected cells incubated with deoxycorticosterone (DOC) alone or DOC plus increasing doses of these steroids. RESULTS: In our in vitro model, both enzymes showed similar apparent kinetic parameters (Km = 1.191 microM and Vmax = 27.08 microM/24 h for ASCE and Km = 1.163 microM and Vmax = 36.98 microM/24 h for ASWT; p = ns, Mann-Whitney test). Progesterone inhibited aldosterone production by ASCE- and ASWT-transfected cells, while estradiol demonstrated no effect. Progesterone acted as a competitive inhibitor for both enzymes. Molecular modelling studies and binding affinity estimations indicate that progesterone might bind to the substrate site in both ASCE and ASWT, supporting the idea that this steroid could regulate these enzymatic activities and contribute to the decay of aldosterone synthase activity in chimeric gene-positive patients. CONCLUSIONS: Our results show an inhibitory action of progesterone in the aldosterone synthesis by chimeric or wild type aldosterone synthase enzymes. This is a novel regulatory mechanism of progesterone action, which could be involved in protecting pregnant women with FH-1 against hypertension. In vitro, both enzymes showed comparable kinetic parameters, but ASWT was more strongly inhibited than ASCE. This study implicates a new role for progesterone in the regulation of aldosterone levels that could contribute, along with other factors, to the maintenance of an adequate aldosterone-progesterone balance in pregnancy.

Disruption of reproductive development in male rat offspring following gestational and lactational exposure to di-(2-ethylhexyl) phthalate and genistein.

Studies of developmental effects of mixtures of endocrine disrupters on the male reproductive system are of great concern. In this study, the reproductive effects of the co-administration of di-2-(ethylhexyl) phthalate (DEHP) and genistein (GEN) during pregnancy and lactation were studied in male rat offspring. Pregnant Sprague-Dawley rats were gavaged from gestation day 3 to postnatal day 21 with vehicle control, DEHP 250 mg/kg body weight (bwyday, GEN 50 mg/kg bwday, GEN 400 mg/kg bwday, and two combinations of the two compounds (DEHP 250 mg/kg bwday + GEN 50 mg/kg bwday, DEHP 250 mg/kg bwday + GEN 400 mg/kg bwday). The outcomes studied were general morphometry (weight, AGD), testicular histology, testosterone levels, and expression at the mRNA level of genes involved in steroidogenesis. Organ coefficient, AGD / body weight1/3 י, serum testosterone concentration and genes involved in steroidogenic pathway expression when exposed to DEHP (250mg/kg bwday), GEN(50mg/kg bwday) or GEN(400mg/kg bwday) alone were not significantly different from the control group. When exposed to (DEHP 250mg/kg bwday +GEN 50mg/kg bwday) together during pregnancy and lactation, serum testosterone concentration, epididymis coefficient and Cypal17a1,Scarb1 m RNA expression significantly decreased compared to the control and GEN(50mg/kg bwday). When exposed to (DEHP 250mg/kg bwday +GEN 400mg/kg bwday) together during pregnancy and lactation, AGD / body weight1/3 י, serum testosterone concentration, testis and epididymis coefficient and Star, Cypal17a1 mRNA expression appeared significantly decreased compared to the control and DEHP/GEN single exposure, together with developmental impairment of seminiferous tubules and seminiferous epithelium. Overall, co-administration of DEHP and GEN during gestation and lactation seem to acts in a cumulative manner to induce the most significant alterations in the neonate, especially with GEN at high dose, although the effect of the DEHP-GEN mixture on adult offspring should be observed further.

Disruption of reproductive development in male rat offspring following gestational and lactational exposure to di-(2-ethylhexyl) phthalate and genistein

Studies of developmental effects of mixtures of endocrine disrupters on the male reproductive system are of great concern. In this study, the reproductive effects of the co-administration of di-2-(ethylhexyl) phthalate (DEHP) and genistein (GEN) during pregnancy and lactation were studied in male rat offspring. Pregnant Sprague-Dawley rats were gavaged from gestation day 3 to postnatal day 21 with vehicle control, DEHP 250 mg/kg body weight (bwyday, GEN 50 mg/kg bwday, GEN 400 mg/kg bwday, and two combinations of the two compounds (DEHP 250 mg/kg bwday + GEN 50 mg/kg bwday, DEHP 250 mg/kg bwday + GEN 400 mg/kg bwday). The outcomes studied were general morphometry (weight, AGD), testicular histology, testosterone levels, and expression at the mRNA level of genes involved in steroidogenesis. Organ coefficient, AGD / body weight1/3 י, serum testosterone concentration and genes involved in steroidogenic pathway expression when exposed to DEHP (250mg/kg bwday), GEN(50mg/kg bwday) or GEN(400mg/kg bwday) alone were not significantly different from the control group. When exposed to (DEHP 250mg/kg bwday +GEN 50mg/kg bwday) together during pregnancy and lactation, serum testosterone concentration, epididymis coefficient and Cypal17a1,Scarb1 m RNA expression significantly decreased compared to the control and GEN(50mg/kg bwday). When exposed to (DEHP 250mg/kg bwday +GEN 400mg/kg bwday) together during pregnancy and lactation, AGD / body weight1/3 י, serum testosterone concentration, testis and epididymis coefficient and Star, Cypal17a1 mRNA expression appeared significantly decreased compared to the control and DEHP/GEN single exposure, together with developmental impairment of seminiferous tubules and seminiferous epithelium. Overall, co-administration of DEHP and GEN during gestation and lactation seem to acts in a cumulative manner to induce the most significant alterations in the neonate, especially with GEN at high dose, although the effect of the DEHP-GEN mixture on adult offspring should be observed further.

A new presentation of the chimeric CYP11B1/CYP11B2 gene with low prevalence of primary aldosteronism and atypical gene segregation pattern.

Familial hyperaldosteronism type I is caused by an unequal crossover of 11ß-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) genes, giving rise to a chimeric CYP11B1/CYP11B2 gene (CG). We describe a family carrying a CG with high levels of free 18-hydroxycortisol but low prevalence of primary aldosteronism (PA) and an atypical CG inheritance pattern in a family of 4 generations with 16 adults and 13 children, we measured the arterial blood pressure, serum aldosterone, and plasma renin activity and then calculated the serum aldosterone:plasma renin activity ratio and urinary free 18-hydroxycortisol. We identified the CG by long-extension PCR and predicted its inheritance pattern. The CG was found in 24 of 29 subjects (10 children and 14 adults). In CG+ patients, hypertension and high 18-hydroxycortisol were prevalent (83% and 100%, respectively). High serum aldosterone:plasma renin activity ratio was more frequent in pediatric than adult patients (80% versus 36%; P<0.001). An inverse association between serum aldosterone:plasma renin activity ratio and age was observed (r=-0.48; P=0.018). Sequence analysis identified the CYP11B1/CYP11B2 crossover in a 50-bp region spanning intron 3 of CYP11B1 and exon 4 of CYP11B2. The CG segregation differs from an autosomal disease, showing 100% of CG penetrance in generations II and III. Statistical analysis suggests that inheritance pattern was not attributed to random segregation (P<0.001). In conclusion, we describe a family with an atypical CYP11B1/CYP11B2 gene inheritance pattern and variable phenotypic expression, where the majority of pediatric patients have primary aldosteronism. Most adults have normal aldosterone and renin levels, which could mask them as essential hypertensives.

Frequency of familial hyperaldosteronism type 1 in a hypertensive pediatric population: clinical and biochemical presentation.

Familial hyperaldosteronism type 1 is an autosomal dominant disorder attributed to a chimeric CYP11B1/CYP11B2 gene (CG). Its prevalence and manifestation in the pediatric population has not been established. We aimed to investigate the prevalence of familial hyperaldosteronism type 1 in Chilean hypertensive children and to describe their clinical and biochemical characteristics. We studied 130 untreated hypertensive children (4 to 16 years old). Blood samples for measuring plasma potassium, serum aldosterone, plasma renin activity, aldosterone/renin ratio, and DNA were collected. The detection of CG was performed using long-extension PCR. We found 4 (3.08%) of 130 children with CG who belonged to 4 unrelated families. The 4 patients with CG had very high aldosterone/renin ratio (49 to 242). In addition, we found 4 children and 5 adults who were affected among 21 first-degree relatives. Of the 8 affected children, 6 presented severe hypertension, 1 presented prehypertension, and 1 presented normotension. High serum aldosterone levels (>17.7 ng/dL) were detected in 6 of 8 subjects (range: 18.6 to 48.4 ng/dL) and suppressed plasma renin activity (≤0.5 ng/mL per hour) and high aldosterone/renin ratio (>10) in 8 of 8 children (range: 49 to 242). Hypokalemia was observed in only 1 of 8 children. We demonstrated that the prevalence of familial hyperaldosteronism type 1 in a pediatric hypertensive pediatric population was surprisingly high. We found a high variability in the clinical and biochemical characteristics of the affected patients, which suggests that familial hyperaldosteronism type 1 is a heterogeneous disease with a wide spectrum of presentations even within the same family group.

Anabolic steroid associated to physical training induces deleterious cardiac effects.

PURPOSE: Cardiac aldosterone might be involved in the deleterious effects of nandrolone decanoate (ND) on the heart. Therefore, we investigated the involvement of cardiac aldosterone, by the pharmacological block of AT1 or mineralocorticoid receptors, on cardiac hypertrophy and fibrosis. METHODS: Male Wistar rats were randomized into eight groups (n = 14 per group): Control (C), nandrolone decanoate (ND), trained (T), trained ND (TND), ND + losartan (ND + L), trained ND + losartan (TND + L), ND + spironolactone (ND + S), and trained ND + spironolactone (TND + S). ND (10 mg·kg(-1)·wk(-1)) was administered during 10 wk of swimming training (five times per week). Losartan (20 mg·kg(-1)·d(-1)) and spironolactone (10 mg·kg(-1)·d(-1)) were administered in drinking water. RESULTS: Cardiac hypertrophy was increased 10% by using ND and 17% by ND plus training (P < 0.05). In both groups, there was an increase in the collagen volumetric fraction (CVF) and cardiac collagen type III expression (P < 0.05). The ND treatment increased left ventricle-angiotensin-converting enzyme I activity, AT1 receptor expression, aldosterone synthase (CYP11B2), and 11-ß hydroxysteroid dehydrogenase 2 (11ß-HSD2) gene expression and inflammatory markers, TGFß and osteopontin. Both losartan and spironolactone inhibited the increase of CVF and collagen type III. In addition, both treatments inhibited the increase in left ventricle-angiotensin-converting enzyme I activity, CYP11B2, 11ß-HSD2, TGFß, and osteopontin induced by the ND treatment. CONCLUSIONS: We believe this is the first study to show the effects of ND on cardiac aldosterone. Our results suggest that these effects may be associated to TGFß and osteopontin. Thus, we conclude that the cardiac aldosterone has an important role on the deleterious effects on the heart induced by ND.

A de novo unequal cross-over mutation between CYP11B1 and CYP11B2 genes causes familial hyperaldosteronism type I.

UNLABELLED: Familial hyperaldosteronism type I (FH-I) is an autosomal dominant disorder caused by an unequal cross-over of the gene encoding steroid 11ß-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2), giving rise to a chimeric CYP11B1/CYP11B2 gene that displays aldosterone synthase activity regulated by ACTH instead of angiotensin II. AIM: To report an unprecedented case of a de novo unequal crossover mutation between CYP11B1 and CYP11B2 genes causing FH-I. PATIENTS AND METHODS: The index case is a 45-yr-old Chilean male diagnosed with primary aldosteronism (PA). All family members were also studied: his biological parents, 1 brother, 6 sisters, 2 daughters, and 1 son. Plasma renin activity, serum aldosterone, and its ratio were measured in all patients. Genetic analyses were performed using long-extension PCR (XL-PCR), DNA sequencing and Southern blot methods. RESULTS: PA was diagnosed for the index case, 1 of his daughters, his son but not for his parents or siblings. XLPCR and Southern blotting demonstrated the presence of the chimeric CYP11B1/CYP11B2 gene solely in PA-affected subjects, suggesting a case of a de novo mutation. Sequence analysis showed the unequal cross-over CYP11B1/CYP11B2 at intron 2 (c.2600-273 CYP11B2). We also identified a polymorphism at the same intron (c.2600-145C>A CYP11B2) in the genome of the index case's father. CONCLUSION: We describe an unprecedented case of unequal cross-over mutation for the chimeric CYP11B1/CYP11B2 gene causing FH-I, which may be linked to a polymorphism in the index case's father germ line.