Disorders of steroid 11 beta-hydroxylase isozymes

Mineralocorticoid receptor antagonist monotherapy in pediatric non-classical 11β-hydroxylase deficiency

OBJECTIVES

Congenital adrenal hyperplasia (CAH) is an uncommon genetic disorder which affects cortisol production in the adrenal glands. It is usually treated with glucocorticoids. We present a case of non-classical CAH caused by the partial deficiency of 11 beta-hydroxylase (11βOH) which was treated with aldosterone antagonist (eplerenone) monotherapy.

CASE PRESENTATION

An adolescent male was diagnosed with 11 beta-hydroxylase deficiency (11βOHD) at 13 years of age when he presented with hypertension, fatigue and headaches. He was initially treated with glucocorticoids, but requested an alternative therapy. Eplerenone was commenced at 25 mg with subsequent dose increases to 100 mg daily. His hypertension was controlled on this regimen, achieving a 24 h average blood pressure of 124/81 mmHg.

CONCLUSIONS

CAH caused by 11βOHD is a known cause of hypertension. It is usually managed with glucocorticoids, and antihypertensives are added if blood pressure remains uncontrolled. In this case, glucocorticoid therapy was not tolerated and treatment with aldosterone antagonist monotherapy was effective in controlling his hypertension.

Metabolic syndrome and cardiovascular morbidity in patients with congenital adrenal hyperplasia

Since the introduction of glucocorticoid (GC) replacement therapy, congenital adrenal hyperplasia (CAH) is no longer a fatal disease. The development of neonatal screening programs and the amelioration of GC treatment strategies have improved significantly life expectancy in CAH patients. Thanks to these achievements, CAH patients are now in their adulthood, but an increased incidence of cardiovascular risk factors has been reported compared to general population in this stage of life. The aim of CAH treatment is to both prevent adrenal insufficiency and suppress androgen excess; in this delicate balance, under- as well as overtreatment might be equally harmful to long-term cardiovascular health. This work examines the prevalence of metabolic features and cardiovascular events, their correlation with hormone levels and GC replacement regimen in CAH patients and focuses on precocious markers to early detect patients at higher risk and new potential treatment approaches.

Disorders of the adrenal cortex: Genetic and molecular aspects

Adrenal cortex produces glucocorticoids, mineralocorticoids and adrenal androgens which are essential for life, supporting balance, immune response and sexual maturation. Adrenocortical tumors and hyperplasias are a heterogenous group of adrenal disorders and they can be either sporadic or familial. Adrenocortical cancer is a rare and aggressive malignancy, and it is associated with poor prognosis. With the advance of next-generation sequencing technologies and improvement of genomic data analysis over the past decade, various genetic defects, either from germline or somatic origin, have been unraveled, improving diagnosis and treatment of numerous genetic disorders, including adrenocortical diseases. This review gives an overview of disorders associated with the adrenal cortex, the genetic factors of these disorders and their molecular implications.

The Expanding Role of Mitochondria, Autophagy and Lipophagy in Steroidogenesis

The fundamental framework of steroidogenesis is similar across steroidogenic cells, especially in initial mitochondrial steps. For instance, the START domain containing protein-mediated cholesterol transport to the mitochondria, and its conversion to pregnenolone by the enzyme P450scc, is conserved across steroidogenic cells. The enzyme P450scc localizes to the inner mitochondrial membrane, which makes the mitochondria essential for steroidogenesis. Despite this commonality, mitochondrial structure, number, and dynamics vary substantially between different steroidogenic cell types, indicating implications beyond pregnenolone biosynthesis. This review aims to focus on the growing roles of mitochondria, autophagy and lipophagy in cholesterol uptake, trafficking and homeostasis in steroidogenic cells and consequently in steroidogenesis. We will focus on these aspects in the context of the physiological need for different steroid hormones and cell-intrinsic inherent features in different steroidogenic cell types beyond mitochondria as a mere site for the beginning of steroidogenesis. The overall goal is to provide an authentic and comprehensive review on the expanding role of steroidogenic cell-intrinsic processes in cholesterol homeostasis and steroidogenesis, and to bring attention to the scientific community working in this field on these promising advancements. Moreover, we will discuss a novel mitochondrial player, prohibitin, and its potential role in steroidogenic mitochondria and cells, and consequently, in steroidogenesis.

Disorders of sex development and female reproductive capacity: A literature review

Disorders of sex development (DSD) are a wide-ranging group of complex conditions that influence chromosomal, gonadal, and phenotypic sex. The prevalence of DSD is very low, but affected patients deserve individualized management to improve psychological, sexual, and reproductive outcomes. This review aims to clarify the fertility potential of DSD patients who can be reared as females and their chance of becoming pregnant, especially using assisted reproductive techniques (ART). Due to the effects of DSD on internal and external genital organs, these conditions result in varying degrees of fertility potential. Fertility rate depends on the phenotype and is inversely related to the severity of the disorder. Reproductive endocrinologists and infertility specialists must be considered active partners of the interdisciplinary treatment team. With current advances in ART, pregnancy is more achievable in patients who were considered infertile at first glance. Due to the complexity of the medical management in DSD patients, more studies should be conducted to conclusively suggest the best choice for improving their fertility potential.Abbreviations: AIS: Androgen Insensitivity Syndrome; AMH: Anti-Müllerian Hormone; ART: Assisted Reproductive Technology; ASRM: American Society for Reproductive Medicine; CAH: Congenital Adrenal Hyperplasia; CAIS: Complete Androgen Insensitivity Syndrome; DHT: Dihydrotestosterone; DSD: Disorders of Sexual Development; FSH: Follicle Stimulating Hormone; GD: Gonadal Dysgenesis; ICSI: Intracytoplasmic Sperm Injection; IUGR: Intrauterine Growth Restriction; IVF: In Vitro Fertilization; IVF-ET: IVF and Embryo Transfer; LH: Luteinizing Hormone; MGD: Mixed Gonadal Dysgenesis; MRI: Magnetic Resonance Imaging; MRKH: Mayer-Rokitansky-Kuster-Hauser; US: Ultrasonography; HSG: Hysterosalpingography; PAIS: Partial Androgen Insensitivity Syndrome; PGD: Preimplantation Genetic Diagnosis; POR: P450 Oxidoreductase; PROM: Premature Rupture of Membranes; TS: Turner Syndrome; 17β-HSD III: 17β-Hydroxysteroid Dehydrogenase III; 21-OHD: 21-hydroxylase deficiency; 5α-RD-2: 5α-reductase-2.

Nonclassic Congenital Adrenal Hyperplasia: What Do Endocrinologists Need to Know?

Congenital adrenal hyperplasia encompasses a group of autosomal recessive defects in cortisol biosynthesis, and 21-hydroxylase deficiency accounts for 95% of such cases. Non-classic 21-hydroxylase deficiency is due to partial enzymatic defects, which present with normal cortisol synthesis, but excessive production of adrenal androgens, including 11-oxygenated androgens. Non-classic 21-hydroxylase deficiency is relatively common, and its phenotype resembles closely that of polycystic ovary syndrome. This review focuses primarily on non-classic 21-hydroxylase deficiency, its clinical features, diagnosis, and management.

Overview of Monogenic or Mendelian Forms of Hypertension

Monogenic or Mendelian forms of hypertension are described as a group of conditions characterized by insults to the normal regulation of blood pressure by the kidney and adrenal gland. These alterations stem from single mutations that lead to maladaptive overabsorption of electrolytes with fluid shift into the vasculature, and consequent hypertension. Knowledge of these various conditions is essential in diagnosing pediatric or early-onset adult hypertension as they directly affect treatment strategies. Precise diagnosis with specific treatment regimens aimed at the underlying physiologic derangement can restore normotension and prevent the severe sequelae of chronic hypertension.

A Chinese patient with 11β-hydroxylase deficiency due to novel compound heterozygous mutation in CYP11B1 gene: a case report

BACKGROUND

Congenital adrenal hyperplasia (CAH) resulting from steroid 11β-hydroxylase deficiency (11β-OHD) is caused by mutations in the CYP11B1 gene. It is the second major form of CAH associated with hypertension and hypopotassemia. The aim of this study was to provide a genetic analysis of 11β-OHD in a Chinese family.

CASE PRESENTATION

A 19-year-old Chinese man was clinically diagnosed with 11β-OHD. His initial clinical manifestations included precocious puberty, hyperpigmentation, hypertension, and hypopotassemia. The patient had taken an overdose of dexamethasone (0.75 mg/d) for more than 10 years before finally developing iatrogenic Cushing's syndrome. Our aim was to perform a molecular diagnosis of his family. Mutations in the CYP11B1 gene of the patient and his parents were examined using polymerase chain reaction (PCR) resequencing. Additionally, to predict the possible effects of novel mutations on the structure and function of 11β-hydroxylase, these mutations were analyzed by MutationTaster software. Two novel pathogenic mutations were found in the CYP11B1 gene: a heterozygous in-frame insertion deletion mutation c.1440_1447delinsTAAAAG in exon 9 inherited from the father and a heterozygous mutation c.1094_1120delTGCGTGCGGCCCTCAAGGAGACCTTGC (p.364_372del) in exon 6 inherited from the mother.

CONCLUSIONS

A clear genetic diagnosis can be made by analyzing the functional and structural consequences of CYP11B1 gene mutations that lead to 11β-OHD. Because the dosage of glucocorticoid should be adjusted to minimize the risk of iatrogenic Cushing's syndrome, clinical follow-up should be conducted with these patients.

The human adrenal cortex: growth control and disorders

This review summarizes key knowledge regarding the development, growth, and growth disorders of the adrenal cortex from a molecular perspective. The adrenal gland consists of two distinct regions: the cortex and the medulla. During embryological development and transition to the adult adrenal gland, the adrenal cortex acquires three different structural and functional zones. Significant progress has been made in understanding the signaling and molecules involved during adrenal cortex zonation. Equally significant is the knowledge obtained regarding the action of peptide factors involved in the maintenance of zonation of the adrenal cortex, such as peptides derived from proopiomelanocortin processing, adrenocorticotropin and N-terminal proopiomelanocortin. Findings regarding the development, maintenance and growth of the adrenal cortex and the molecular factors involved has improved the scientific understanding of disorders that affect adrenal cortex growth. Hypoplasia, hyperplasia and adrenocortical tumors, including adult and pediatric adrenocortical adenomas and carcinomas, are described together with findings regarding molecular and pathway alterations. Comprehensive genomic analyses of adrenocortical tumors have shown gene expression profiles associated with malignancy as well as methylation alterations and the involvement of miRNAs. These findings provide a new perspective on the diagnosis, therapeutic possibilities and prognosis of adrenocortical disorders.

Monogenic Disorders of Adrenal Steroidogenesis

Disorders of adrenal steroidogenesis comprise autosomal recessive conditions affecting steroidogenic enzymes of the adrenal cortex. Those are located within the 3 major branches of the steroidogenic machinery involved in the production of mineralocorticoids, glucocorticoids, and androgens. This mini review describes the principles of adrenal steroidogenesis, including the newly appreciated 11-oxygenated androgen pathway. This is followed by a description of pathophysiology, biochemistry, and clinical implications of steroidogenic disorders, including mutations affecting cholesterol import and steroid synthesis, the latter comprising both mutations affecting steroidogenic enzymes and co-factors required for efficient catalysis. A good understanding of adrenal steroidogenic pathways and their regulation is crucial as the basis for sound management of these disorders, which in the majority present in early childhood.

Stimulatory Effect of Intermittent Hypoxia on the Production of Corticosterone by Zona Fasciculata-Reticularis Cells in Rats

Hypoxia or intermittent hypoxia (IH) have known to alter both synthesis and secretion of hormones. However, the effect of IH on the production of adrenal cortical steroid hormones is still unclear. The aim of present study was to explore the mechanism involved in the effect of IH on the production of corticosterone by rat ZFR cells. Male rats were exposed at 12% O₂ and 88% N₂ (8 hours per day) for 1, 2, or 4 days. The ZFR cells were incubated at 37 °C for 1 hour with or without ACTH, 8-Br-cAMP, calcium ion channel blockers, or steroidogenic precursors. The concentration of plasma corticosterone was increased time-dependently by administration of IH hypoxia. The basal levels of corticosterone production in cells were higher in the IH groups than in normoxic group. IH resulted in a time-dependent increase of corticosterone production in response to ACTH, 8-Br-cAMP, progesterone and deoxycorticosterone. The production of pregnenolone in response to 25-OH-C and that of progesterone in response to pregnenolone in ZFR cells were enhanced by 4-day IH. These results suggest that IH in rats increases the secretion of corticosterone via a mechanism at least in part associated with the activation of cAMP pathway and steroidogenic enzymes.

ACTH and Polymorphisms at Steroidogenic Loci as Determinants of Aldosterone Secretion and Blood Pressure

The majority of genes contributing to the heritable component of blood pressure remain unidentified, but there is substantial evidence to suggest that common polymorphisms at loci involved in the biosynthesis of the corticosteroids aldosterone and cortisol are important. This view is supported by data from genome-wide association studies that consistently link the CYP17A1 locus to blood pressure. In this review article, we describe common polymorphisms at three steroidogenic loci (CYP11B2, CYP11B1 and CYP17A1) that alter gene transcription efficiency and levels of key steroids, including aldosterone. However, the mechanism by which this occurs remains unclear. While the renin angiotensin system is rightly regarded as the major driver of aldosterone secretion, there is increasing evidence that the contribution of corticotropin (ACTH) is also significant. In light of this, we propose that the differential response of variant CYP11B2, CYP11B1 and CYP17A1 genes to ACTH is an important determinant of blood pressure, tending to predispose individuals with an unfavourable genotype to hypertension.

Clinical perspectives in congenital adrenal hyperplasia due to 11β-hydroxylase deficiency

Congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency is a rare autosomal recessive genetic disorder. It is caused by reduced or absent activity of 11β-hydroxylase (CYP11B1) enzyme and the resultant defects in adrenal steroidogenesis. The most common clinical features of 11 beta-hydroxylase deficiency are ambiguous genitalia, accelerated skeletal maturation and resultant short stature, peripheral precocious puberty and hyporeninemic hypokalemic hypertension. The biochemical diagnosis is based on raised serum 11-deoxycortisol and 11-deoxycorticosterone levels together with increased adrenal androgens. More than 100 mutations in CYP11B1 gene have been reported to date. The level of in-vivo activity of CYP11B1 relates to the degree of severity of 11 beta-hydroxylase deficiency. Clinical management of 11 beta-hydroxylase deficiency can pose a challenge to maintain adequate glucocorticoid dosing to suppress adrenal androgen excess while avoiding glucocorticoid-induced side effects. The long-term outcomes of clinical and surgical management are not well studied. This review article aims to collate the current available data about 11 beta-hydroxylase deficiency and its management.

Genetic Programming of Hypertension

The heritability of hypertension (HTN) is widely recognized and as a result, extensive studies ranging from genetic linkage analyses to genome-wide association studies are actively ongoing to elucidate the etiology of both monogenic and polygenic forms of HTN. Due to the complex nature of essential HTN, however, single genes affecting blood pressure (BP) variability remain difficult to isolate and identify and have rendered the development of single-gene targeted therapies challenging. The roles of other causative factors in modulating BP, such as gene-environment interactions and epigenetic factors, are increasingly being brought to the forefront. In this review, we discuss the various monogenic HTN syndromes and corresponding pathophysiologic mechanisms, the different methodologies employed in genetic studies of essential HTN, the mechanisms for epigenetic modulation of essential HTN, pharmacogenomics and HTN, and finally, recent advances in genetic studies of essential HTN in the pediatric population.

Corticosterone Methyl Oxidase Deficiency Type 1 with Normokalemia in an Infant

Isolated aldosterone synthase deficiency may result in life-threatening salt-wasting and failure to thrive. The condition involves hyperkalemia accompanying hyponatremia. Two types of aldosterone synthase deficiency may be observed depending on hormone levels: corticosterone methyl oxidase type 1 (CMO 1) and CMO 2. Herein, we describe a Turkish infant patient with aldosterone synthase deficiency who presented with failure to thrive and salt wasting but with normal potassium levels. Urinary steroid characteristics were compatible with CMO I deficiency. Diagnosis of aldosterone synthase deficiency was confirmed by mutational analysis of the CYP11B2 gene which identified the patient as homozygous for two mutations: c.788T>A (p.Ile263Asn) and c.1157T>C (p.Val386Ala). Family genetic study revealed that the mother was heterozygous for c.788T>A and homozygous for c.1157T>C and the father was heterozygous for both c.788T>A and c.1157T>C. To the best of our knowledge, this is only the second Turkish case with a confirmed molecular basis of type 1 aldosterone synthase deficiency. This case is also significant in showing that spot urinary steroid analysis can assist with the diagnosis and that hyperkalemia is not necessarily part of the disease.

Improving the diagnosis of 11β-hydroxylase deficiency using home-made MLPA probes: identification of a novel chimeric CYP11B2/CYP11B1 gene in a Sicilian patient

PURPOSE

11β-Hydroxylase deficiency (11OHD) represents the second most common cause of congenital adrenal hyperplasia. It is caused by mutations in the CYP11B1 gene localized about 40 kb from the CYP11B2 gene with which it shares a homology of 95 %. The asymmetric recombination of these two genes is involved both in 11OHD and in glucocorticoid-remediable aldosteronism (GRA). Our objective was to set up an easy and rapid method to detect these hybrid genes and other kinds of deletions, to improve the molecular diagnosis of 11OHD.

METHODS

A set of 8 specific probes for both the CYP11B1 and the CYP11B2 genes to be used for multiplex ligation-dependent probe amplification (MLPA) analysis was designed to detect rearrangements of these genes.

RESULTS

The method developed was tested on 15 healthy controls and was proved to be specific and reliable; it led us to identify a novel chimeric CYP11B2/CYP11B1 gene in one patient that carried the known A306V mutation on the other allele. Specific amplification and sequencing of the hybrid gene confirmed the breakpoint localization in the second intron.

CONCLUSIONS

The MLPA kit developed enables the detection of deletions, duplications or chimeric genes and represents an optimal supplement to DNA sequence analysis in patients with 11OHD. In addition, it can also be used to show the presence of the opposite chimaera associated with GRA.

A Greek girl with 11β-hydroxylase deficiency due to compound heterozygosity for two novel mutations in CYP11B1 gene

11β-hydroxylase deficiency (11β-OHD), an autosomal recessive inherited disorder, accounts for 5–8% of congenital adrenal hyperplasia. In Greece, no cases of 11β-OHD have been described so far. The patient presented at the age of 13 months with mild virilization of external genitalia and pubic hair development since the age of 3 months. Hormonal profile showed elevated 11-deoxycortisol, adrenal androgens and ACTH levels. ACTH stimulation test was compatible with 11β-OHD. DNA of the proband and her parents was isolated and genotyped for CYP11B1 gene coding cytochrome P450c11. The girl was found to be compound heterozygous for two CYP11B1 novel mutations, p.Ala386Glu (exon 7), inherited from the father and p.Leu471Argin (exon 9) from the mother. Hydrocortisone supplementation therapy was initiated. Four years after presentation she remains normotensive, her growth pattern is normal and the bone age remains advanced despite adequate suppression of adrenal androgens.

The next 150 years of congenital adrenal hyperplasia

Congenital adrenal hyperplasias (CAH) are a group of autosomal recessive defects in cortisol biosynthesis. Substantial progress has been made since the description of the first report, 150 years ago. This article reviews some of the recent advances in the genetics, diagnosis and treatment of CAH. In addition, we underline the aspects where further progress is required, including, among others, better diagnostic modalities for the mild phenotype and for some of the rare forms of disease, elucidation of epigenetic factors that lead to different phenotypes in patients with identical genotype and expending on treatment options for controlling the adrenal androgen excess.

A Novel Mutation in the CYP11B1 Gene Causes Steroid 11β-Hydroxylase Deficient Congenital Adrenal Hyperplasia with Reversible Cardiomyopathy

Congenital adrenal hyperplasia (CAH) due to steroid 11β-hydroxylase deficiency is the second most common form of CAH, resulting from a mutation in the CYP11B1 gene. Steroid 11β-hydroxylase deficiency results in excessive mineralcorticoids and androgen production leading to hypertension, precocious puberty with acne, enlarged penis, and hyperpigmentation of scrotum of genetically male infants. In the present study, we reported 3 male cases from a Saudi family who presented with penile enlargement, progressive darkness of skin, hypertension, and cardiomyopathy. The elder patient died due to heart failure and his younger brothers were treated with hydrocortisone and antihypertensive medications. Six months following treatment, cardiomyopathy disappeared with normal blood pressure and improvement in the skin pigmentation. The underlying molecular defect was investigated by PCR-sequencing analysis of all coding exons and intron-exon boundary of the CYP11B1 gene. A novel biallelic mutation c.780 G>A in exon 4 of the CYP11B1 gene was found in the patients. The mutation created a premature stop codon at amino acid 260 (p.W260 (∗) ), resulting in a truncated protein devoid of 11β-hydroxylase activity. Interestingly, a somatic mutation at the same codon (c.779 G>A, p.W260 (∗) ) was reported in a patient with papillary thyroid cancer (COSMIC database). In conclusion, we have identified a novel nonsense mutation in the CYP11B1 gene that causes classic steroid 11β-hydroxylase deficient CAH. Cardiomyopathy and cardiac failure can be reversed by early diagnosis and treatment.

Physiological basis for the etiology, diagnosis, and treatment of adrenal disorders: Cushing's syndrome, adrenal insufficiency, and congenital adrenal hyperplasia

The hypothalamic-pituitary-adrenal (HPA) axis is a classic neuroendocrine system. One of the best ways to understand the HPA axis is to appreciate its dynamics in the variety of diseases and syndromes that affect it. Excess glucocorticoid activity can be due to endogenous cortisol overproduction (spontaneous Cushing's syndrome) or exogenous glucocorticoid therapy (iatrogenic Cushing's syndrome). Endogenous Cushing's syndrome can be subdivided into ACTH-dependent and ACTH-independent, the latter of which is usually due to autonomous adrenal overproduction. The former can be due to a pituitary corticotroph tumor (usually benign) or ectopic ACTH production from tumors outside the pituitary; both of these tumor types overexpress the proopiomelanocortin gene. The converse of Cushing's syndrome is the lack of normal cortisol secretion and is usually due to adrenal destruction (primary adrenal insufficiency) or hypopituitarism (secondary adrenal insufficiency). Secondary adrenal insufficiency can also result from a rapid discontinuation of long-term, pharmacological glucocorticoid therapy because of HPA axis suppression and adrenal atrophy. Finally, mutations in the steroidogenic enzymes of the adrenal cortex can lead to congenital adrenal hyperplasia and an increase in precursor steroids, particularly androgens. When present in utero, this can lead to masculinization of a female fetus. An understanding of the dynamics of the HPA axis is necessary to master the diagnosis and differential diagnosis of pituitary-adrenal diseases. Furthermore, understanding the pathophysiology of the HPA axis gives great insight into its normal control.

Characterisation of three novel CYP11B1 mutations in classic and non-classic 11β-hydroxylase deficiency

BACKGROUND

Congenital adrenal hyperplasia (CAH) is one of the most common autosomal recessive inherited endocrine diseases. Steroid 11β-hydroxylase (P450c11) deficiency (11OHD) is the second most common form of CAH.

AIM

The aim of the study was to study the functional consequences of three novel CYP11B1 gene mutations (p.His125Thrfs*8, p.Leu463_Leu464dup and p.Ser150Leu) detected in patients suffering from 11OHD and to correlate this data with the clinical phenotype.

METHODS

Functional analyses were done by using a HEK293 cell in vitro expression system comparing WT with mutant P450c11 activity. Mutant proteins were examined in silico to study their effect on the three-dimensional structure of the protein.

RESULTS

Two mutations (p.His125Thrfs*8 and p.Leu463_Leu464dup) detected in patients with classic 11OHD showed a complete loss of P450c11 activity. The mutation (p.Ser150Leu) detected in a patient with non-classic 11OHD showed partial functional impairment with 19% of WT activity.

CONCLUSION

Functional mutation analysis enables the correlation of novel CYP11B1 mutations to the classic and non-classic 11OHD phenotype respectively. Mutations causing a non-classic phenotype show typically partial impairment due to reduced maximum reaction velocity comparable with non-classic mutations in 21-hydroxylase deficiency. The increasing number of mutations associated with non-classic 11OHD illustrate that this disease should be considered as diagnosis in patients with otherwise unexplained hyperandrogenism.

Gene mutations that promote adrenal aldosterone production, sodium retention, and hypertension

Primary aldosteronism (PA) is the most common form of secondary hypertension, found in about 5% of all hypertension cases, and up to 20% of resistant hypertension cases. The most common forms of PA are an aldosterone-producing adenoma and idiopathic (bilateral) hyperaldosteronism. Rare genetic forms of PA exist and, until recently, the only condition with a known genetic mechanism was familial hyperaldosteronism type 1, also known as glucocorticoid-remediable aldosteronism (FHA1/GRA). FHA type 3 has now been shown to derive from germline mutations in the KCNJ5 gene, which encodes a potassium channel found on the adrenal cells. Remarkably, somatic mutations in KCNJ5 are found in about one-third of aldosterone-producing adenomas, and these mutations are likely to be involved in their pathogenesis. Finally, mutations in the genes encoding an L-type calcium channel (CACNA1D) and in genes encoding a sodium–potassium adenosine triphosphatase (ATP1A1) or a calcium adenosine triphosphatase (ATP2B3) are found in other aldosterone-producing adenomas. These findings provide a working model, in which adenoma formation and/or aldosterone production in many cases derives from increased calcium entry, which drives the pathogenesis of primary aldosteronism.

Congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency: functional consequences of four CYP11B1 mutations

Congenital adrenal hyperplasia (CAH) is one of the most common autosomal recessive inherited endocrine disease. Steroid 11β-hydroxylase deficiency (11β-OHD) is the second most common form of CAH. The aim of the study was to study the functional consequences of three novel and one previously described CYP11B1 gene mutations (p.(Arg143Trp), p.(Ala306Val), p.(Glu310Lys) and p.(Arg332Gln)) detected in patients suffering from classical and non-classical 11β-OHD. Functional analyses were performed by using a HEK293 cell in vitro expression system comparing wild type (WT) with mutant 11β-hydroxylase activity. Mutant proteins were examined in silico to study their effect on the three-dimensional structure of the protein. Two mutations (p.(Ala306Val) and p.(Glu310Lys)) detected in patients with classical 11β-OHD showed a nearly complete loss of 11β-hydroxylase activity. The mutations p.(Arg143Trp) and p.(Arg332Gln) detected in patients with non-classical 11β-OHD showed a partial functional impairment with approximately 8% and 6% of WT activity, respectively. Functional mutation analysis allows the classification of novel CYP11B1 mutations as causes of classical and non-classical 11β-OHD. The detection of patients with non-classical phenotypes underscores the importance to screen patients with a phenotype comparable to non-classical 21-hydroxylase deficiency for mutations in the CYP11B1 gene in case of a negative analysis of the CYP21A2 gene. As CYP11B1 mutations are most often individual for a family, the in vitro analysis of novel mutations is essential for clinical and genetic counselling.

Cytochromes p450: roles in diseases

The cytochrome P450 superfamily consists of a large number of heme-containing monooxygenases. Many human P450s metabolize drugs used to treat human diseases. Others are necessary for synthesis of endogenous compounds essential for human physiology. In some instances, alterations in specific P450s affect the biological processes that they mediate and lead to a disease. In this minireview, we describe medically significant human P450s (from families 2, 4, 7, 11, 17, 19, 21, 24, 27, 46, and 51) and the diseases associated with these P450s.

Roux-en-Y gastric bypass in the treatment of non-classic congenital adrenal hyperplasia due to 11-hydroxylase deficiency

Non-classic adrenal hyperplasia (NCAH) has been associated with insulin resistance (IR). Therapies such as metformin, thiazolidinediones and lifestyle alterations improve IR and also ameliorate the biochemical and clinical abnormalities of NCAH, much as they do in polycystic ovarian syndrome (PCOS). More recently, bariatric surgery, such as Roux-en-Y gastric bypass (RYGBP), has also been associated with improvement in IR and amelioration of PCOS and may, therefore, be beneficial in NCAH. We report a case of a 39-year-old, deaf-mute, obese woman with NCAH due to 11-hydroxylase deficiency who underwent RYGBP followed by improvement of NCAH manifestations. She was initially treated with metformin and pioglitazone, which lowered serum 11-deoxycortisol from 198 ng/dl (<51) to 26 ng/dl. Five weeks after undergoing RYGBP her body mass index fell from 44.18 kg/m(2) to 39.54 kg/m(2) and, despite not taking metformin or pioglitazone, serum 11-deoxycortisol remained normal at <40 ng/dl. Concurrently and subsequently, her NCAH symptoms, for example, alopecia, hirsutism and irregular menses normalised as well. We conclude that RYGBP, like other interventions that reduce IR, may be another way of treating non-classic 11-hydroxylase deficiency in selected patients.

Human cytochromes P450 in health and disease

There are 18 mammalian cytochrome P450 (CYP) families, which encode 57 genes in the human genome. CYP2, CYP3 and CYP4 families contain far more genes than the other 15 families; these three families are also the ones that are dramatically larger in rodent genomes. Most (if not all) genes in the CYP1, CYP2, CYP3 and CYP4 families encode enzymes involved in eicosanoid metabolism and are inducible by various environmental stimuli (i.e. diet, chemical inducers, drugs, pheromones, etc.), whereas the other 14 gene families often have only a single member, and are rarely if ever inducible or redundant. Although the CYP2 and CYP3 families can be regarded as largely redundant and promiscuous, mutations or other defects in one or more genes of the remaining 16 gene families are primarily the ones responsible for P450-specific diseases-confirming these genes are not superfluous or promiscuous but rather are more directly involved in critical life functions. P450-mediated diseases comprise those caused by: aberrant steroidogenesis; defects in fatty acid, cholesterol and bile acid pathways; vitamin D dysregulation and retinoid (as well as putative eicosanoid) dysregulation during fertilization, implantation, embryogenesis, foetogenesis and neonatal development.

Low renin hypertension

Low renin hypertension is an important and often underdiagnosed cause of hypertension. It may be associated with high aldosterone levels as in Conn's syndrome or low aldosterone levels as in Liddle syndrome, and syndrome of apparent mineralocorticoid excess, glucocorticoid remediable hypertension etc. Some forms of essential hypertension are also associated with low renin levels. Hypokalemia may be an important finding in low renin hypertension. The aldosterone to renin ratio helps in correct diagnosis. The treatment varies with etiology hence an accurate diagnosis is essential. Aldosterone antagonists play an important role in medical management of some varieties of low renin hypertension.

Left ventricular failure due to a rare variant of congenital adrenal hyperplasia

"Hypertensive" variant of congenital adrenal hyperplasia is rare. The authors describe an interesting case of a 6-y-old boy who presented with an acute respiratory illness and progressive breathlessness since 1 y. Genital hyperpigmentation was noticed since 2 y of age; the onset of pubarche and increasing penile size at 4 y. He was admitted in congestive cardiac failure with a blood pressure of 150/100 mm Hg. Facial acne; slight facial, pubic hair and penile enlargement were additionally noted. Chest radiograph revealed cardiomegaly. Basal ACTH and 17-OHP levels were high. A diagnosis of congenital adrenal hyperplasia (11β-hydroxylase deficiency) was made due to hypertension with virilized genitalia. Cardiac failure was controlled with fluid restriction and diuretics; he was started on prednisolone, spironolactone and nifedipine. This case is presented for its rarity where hypertension can cause complication of cardiac failure, if diagnosis is delayed despite early features of pseudoprecocious puberty.

Functional consequences of seven novel mutations in the CYP11B1 gene: four mutations associated with nonclassic and three mutations causing classic 11{beta}-hydroxylase deficiency

CONTEXT

Steroid 11beta-hydroxylase (CYP11B1) deficiency (11OHD) is the second most common form of congenital adrenal hyperplasia (CAH). Cases of nonclassic 11OHD are rare compared with the incidence of nonclassic 21-hydroxylase deficiency.

OBJECTIVE

The aim of the study was to analyze the functional consequences of seven novel CYP11B1 mutations (p.M88I, p.W116G, p.P159L, p.A165D, p.K254_A259del, p.R366C, p.T401A) found in three patients with classic 11OHD, two patients with nonclassic 11OHD, and three heterozygous carriers for CYP11B1 mutations.

METHODS

We conducted functional studies employing a COS7 cell in vitro expression system comparing wild-type (WT) and mutant CYP11B1 activity. Mutants were examined in a computational three-dimensional model of the CYP11B1 protein.

RESULTS

All mutations (p.W116G, p.A165D, p.K254_A259del) found in patients with classic 11OHD have absent or very little 11beta-hydroxylase activity relative to WT. The mutations detected in patients with nonclassic 11OHD showed partial functional impairment, with one patient being homozygous (p.P159L; 25% of WT) and the other patient compound heterozygous for a novel mild p.M88I (40% of WT) and the known severe p.R383Q mutation. The two mutations detected in heterozygous carriers (p.R366C, p.T401A) also reduced CYP11B1 activity by 23 to 37%, respectively.

CONCLUSION

Functional analysis results allow for the classification of novel CYP11B1 mutations as causative for classic and nonclassic 11OHD, respectively. Four partially inactivating mutations are predicted to result in nonclassic 11OHD. These findings double the number of mild CYP11B1 mutations previously described as associated with mild 11OHD. Our data are important to predict phenotypic expression and provide important information for clinical and genetic counseling in 11OHD.

Genetics of congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is one of the most common inherited metabolic disorders. It comprises a group of autosomal recessive disorders caused by the deficiency of one of four steroidogenic enzymes involved in cortisol biosynthesis or in the electron donor enzyme P450 oxidoreductase (POR) that serves as electron donor to steroidogenic cytochrome P450 (CYP) type II enzymes. The biochemical and clinical phenotype depends on the specific enzymatic defect and the impairment of specific enzyme activity. Defects of steroid 21-hydroxylase (CYP21A2) and 11beta-hydroxylase (CYP11B1) only affect adrenal steroidogenesis, whereas 17alpha-hydroxylase (CYP17A1) and 3beta-hydroxysteroid dehydrogenase type 2 (HSD3B2) deficiency also impact on gonadal steroid biosynthesis. Inactivating POR gene mutations are the cause of CAH manifesting with apparent combined CYP17A1-CYP21A2 deficiency. P450 oxidoreductase deficiency (ORD) has a complex phenotype including two unique features not observed in any other CAH variant: skeletal malformations and severe genital ambiguity in both sexes.

Androgen synthesis in adrenarche

The enzymes and pathways of steroidogenesis are central to an understanding of adrenarche. The quantitative regulation of steroidogenesis occurs at the first step, the conversion of cholesterol to pregnenolone. Chronic quantitative regulation is principally at the level of transcription of the CYP11A1 gene encoding P450scc, which is the enzymatically rate-limiting step. Acute regulation is mediated by the steroidogenic acute regulatory protein (StAR), which facilitates the rapid influx of cholesterol into mitochondria, where P450scc resides. Qualitative regulation, which determines the type of steroid produced in a cell, is principally at the level of P450c17 (CYP17). In the absence of P450c17 in the zona glomerulosa, C21 deoxy steroids are produced, leading to the mineralocorticoid, aldosterone. In the presence of the 17alpha-hydroxylase but not the 17,20 lyase activity of P450c17 in the zona fasciculata, C21, 17-hydroxy steroids are produced, leading to the glucocorticoid, cortisol. When both the 17alpha-hydroxylase and 17,20 lyase activities of P450c17 are present in the zona reticularis, the androgen precursor DHEA is produced. The discrimination between 17alpha-hydroxylase and 17,20 lyase activities is regulated by two post-translational events, the serine phosphorylation of P450c17 and the allosteric action of cytochrome b5, both of which act to optimize the interaction of P450c17 with its obligatory electron donor, P450 oxidoreductase. In the adrenal zona reticularis, the abundant expression of P450 oxidoreductase and cytochrome b5, and the low expression of 3beta-hydroxysteroid dehydrogenase (HSD3B2) result in the production of the large amounts of DHEA that characterize adrenarche.

Detection of cortisol in saliva with a flow-filtered, portable surface plasmon resonance biosensor system

Saliva provides a useful and noninvasive alternative to blood for many biomedical diagnostic assays. The level of the hormone cortisol in blood and saliva is related to the level of stress. We present here the development of a portable surface plasmon resonance (SPR) biosensor system for detection of cortisol in saliva. Cortisol-specific monoclonal antibodies were used to develop a competition assay with a six-channel portable SPR biosensor designed in our laboratory. The detection limit of cortisol in laboratory buffers was 0.36 ng/mL (1.0 nM). An in-line filter based on diffusion through a hollow fiber hydrophilic membrane served to separate small molecules from the complex macromolecular matrix of saliva prior to introduction to the sensor surface. The filtering flow cell provided in-line separation of small molecules from salivary mucins and other large molecules with only a 29% reduction of signal compared with direct flow of the same concentration of analyte over the sensor surface. A standard curve for detection of cortisol in saliva was generated with a detection limit of 1.0 ng/mL (3.6 nM), sufficiently sensitive for clinical use. The system will also be useful for a wide range of applications where small molecular weight analytes are found in complex matrixes.

Basic concepts and recent developments in human steroid hormone biosynthesis

The biosynthesis of steroid hormones requires the coordinated expression of the enzymes that comprise the pathways via which specific hormones are synthesized. These pathways and their associated enzymes are typically subject to regulation consisting of trophic hormone stimuli and feedback mechanisms. Very few tissues contribute substantially to de novo steroidogenesis, primarily the adrenal glands, the gonads, and the placenta. Both the embryonic origins and the signaling mechanisms for the adrenals and gonads are similar, and steroid synthesis in these two glands are the major focus of this review. We will further describe peripheral steroid metabolism and the regulation of steroid hormone potency in target tissues. In addition, we will briefly discuss the congenital adrenal hyperplasias to illustrate the principles developed in the initial sections. Finally, we will discuss some recent developments in steroidogensis, focusing on cytochrome P450 oxidoreductase deficiency and the alternate or "backdoor" pathway to dihydrotestosterone. We will conclude with a description of aberrant signaling mechanisms observed in adrenal tumors as a further example of how these pathways can be disturbed in pathologic states.

Miscellaneous endocrine causes of hypertension

Aldosterone is the principal circulating mineralocorticoid in humans, and aldosterone synthesis normally occurs in the face of volume depletion and renin stimulation. In primary and secondary aldosteronism, aldosterone synthesis continues despite volume expansion and causes hypertension. Other steroid hormones that are aldosterone and cortisol precursors also activate the mineralocorticoid receptor and cause hypertension when overproduced. Mineralocorticoid synthesis in these pathologic states can be constitutive or driven by pituitary adrenocorticotropic hormone (ACTH), due to genetic defects that cause disordered steroid synthesis or catabolism. This review focuses on uncommon forms of ACTH-dependent mineralocorticoid excess states associated with hypertension.

CHARACTERIZATION OF TESTOSTERONE 11β-HYDROXYLATION CATALYZED BY HUMAN LIVER MICROSOMAL CYTOCHROMES P450

A combination of accelerator mass spectrometry (AMS) and liquid chromatography-tandem mass spectrometry has been used to clarify some new aspects of testosterone metabolism. The main pathway of testosterone oxidative metabolism by human liver microsomes is the formation of 1beta-, 2alpha-/beta-, 6beta-, 15beta-, and 16beta-hydroxytestosterones, mainly catalyzed by cytochromes P450 2C9, 2C19, and 3A4. We now report the first determination that 11beta-hydroxytestosterone (11beta-OHT) can also be formed by human liver microsomal fractions. The structures of five hydroxylated metabolites of testosterone (2beta-, 6beta-, 11beta-, 15beta-, and 16beta-OHT) and the C-17 oxidative metabolite androstenedione were determined by liquid chromatography with UV detection at 240 nm and liquid chromatography-tandem mass spectrometry. Corresponding results were obtained by high-performance liquid chromatography-AMS analysis of incubations of [4-14C]testosterone with human liver microsomes. 6beta-Hydroxylation was always the dominant metabolic pathway, but 2beta-, 15beta-, and 16beta-OHT, and androstenedione were also formed. The previously undetected hydroxytestosterone, 11beta-OHT, was found to be a minor metabolite formed by human liver microsomal enzymes. It was formed more readily by CYP3A4 than by either CYP2C9 or CYP2C19. 11beta-Hydroxylation was inhibited by ketoconazole (IC50 = 30 nM) at concentrations similar to the IC50 (36 nM) for 6beta-hydroxylation Therefore, CYP3A4 could be mainly responsible for testosterone 11beta-hydroxylation in the human liver. These findings identify human hepatic biotransformation of testosterone to 11beta-OHT as a previously unrecognized extra-adrenal metabolic pathway.

Positron emission tomography imaging of adrenal masses: (18)F-fluorodeoxyglucose and the 11beta-hydroxylase tracer (11)C-metomidate

PURPOSE

(11)C-metomidate (MTO), a marker of 11beta-hydroxylase, has been suggested as a novel positron emission tomography (PET) tracer for adrenocortical imaging. Up to now, experience with this very new tracer is limited. The aims of this study were (1) to evaluate this novel tracer, (2) to point out possible advantages in comparison with( 18)F-fluorodeoxyglucose (FDG) and (3) to investigate in vivo the expression of 11beta-hydroxylase in patients with primary aldosteronism.

METHODS

Sixteen patients with adrenal masses were investigated using both MTO and FDG PET imaging. All patients except one were operated on. Five patients had non-functioning adrenal masses, while 11 had functioning tumours(Cushing's syndrome, n=4; Conn's syndrome, n=5; phaeochromocytoma, n=2). Thirteen patients had benign disease, whereas in three cases the adrenal mass was malignant (adrenocortical cancer, n=1; malignant phaeochromocytoma, n=1; adrenal metastasis of renal cancer, n=1).

RESULTS

MTO imaging clearly distinguished cortical from non-cortical adrenal masses (median standardised uptake values of 18.6 and 1.9, respectively, p<0.01). MTO uptake was slightly lower in patients with Cushing's syndrome than in those with Conn's syndrome, but the difference did not reach statistical significance. The expression of 11beta-hydroxylase was not suppressed in the contralateral gland of patients with Conn's syndrome, whereas in Cushing's syndrome this was clearly the case. The single patient with adrenocortical carcinoma had MTO uptake in the lower range.

CONCLUSION

MTO could not definitely distinguish between benign and malignant disease. FDG PET, however, identified clearly all three study patients with malignant adrenal lesions. We conclude: (1) MTO is an excellent imaging tool to distinguish adrenocortical and non-cortical lesions; (2) the in vivo expression of 11beta-hydroxylase is lower in Cushing's syndrome than in Conn's syndrome, and there is no suppression of the contralateral gland in primary aldosteronism; (3) for the purpose of discriminating between benign and malignant lesions, FDG is the tracer of choice.

A novel genetic locus for low renin hypertension: familial hyperaldosteronism type II maps to chromosome 7 (7p22)

Familial hyperaldosteronism type II (FH-II) is caused by adrenocortical hyperplasia or aldosteronoma or both and is frequently transmitted in an autosomal dominant fashion. Unlike FH type I (FH-I), which results from fusion of the CYP11B1 and CYP11B2 genes, hyperaldosteronism in FH-II is not glucocorticoid remediable. A large family with FH-II was used for a genome wide search and its members were evaluated by measuring the aldosterone:renin ratio. In those with an increased ratio, FH-II was confirmed by fludrocortisone suppression testing. After excluding most of the genome, genetic linkage was identified with a maximum two point lod score of 3.26 at theta=0, between FH-II in this family and the polymorphic markers D7S511, D7S517, and GATA24F03 on chromosome 7, a region that corresponds to cytogenetic band 7p22. This is the first identified locus for FH-II; its molecular elucidation may provide further insight into the aetiology of primary aldosteronism.

Genetic determination of plasma aldosterone levels in essential hypertension

The renin-angiotensin-aldosterone system plays an important role in large artery structure and blood pressure homeostasis. Among the genes coding for different components of this system, the aldosterone synthase (CYP11B2) gene could play an important role, but has been less investigated. We examined the role of two variations of the aldosterone synthase gene (CYP11B2), one located in the promoter of the gene, T-344C, the other in the 7th exon, the T4986C (Val/Ala), on plasma levels of renin and aldosterone, blood pressure, and arterial stiffness in subjects with essential hypertension. Subjects of European origin (n = 216) were examined during a 1-day hospitalization. Treatment, if any, was interrupted for at least 21 days before. Arterial stiffness was evaluated by measuring pulse wave velocity. Renin and aldosterone levels were evaluated by using a radioimmunoassay. The two polymorphisms were in complete linkage disequilibrium, as suggested by the presence of only three haplotypes in this population (T-344T4986, T-344C4986, and C-344T4986). The mean age and blood pressure values were similar in the different genotypes. Presence of the -344C allele was associated with elevated levels of plasma aldosterone: 90 +/- 8 pg/mL for TT (n = 67), 110 +/- 6 pg/mL for TC (n = 107), and 129 +/- 10 pg/mL for CC (n = 42) (test of codominant effect, P < .002 after adjustment for age and 24-h Na+ urine excretion). Pulse wave velocity was also increased in the -344C allele carriers: 11.3 +/- 0.4 m/sec, 12.7 +/- 0.3 m/sec, 12.0 +/- 0.5 m/sec in the TT, TC, and CC genotypes, respectively. No association was found between the T4986C polymorphism and the studied variables. In patients with essential hypertension, a variant on the promoter region of the aldosterone synthase gene is associated with significant differences in plasma aldosterone levels and arterial stiffness. These differences are not associated with variations in blood pressure levels.

CYP11B1 mutations causing non-classic adrenal hyperplasia due to 11 beta-hydroxylase deficiency

Steroid 11 beta-hydroxylase deficiency is the second most common cause of congenital adrenal hyperplasia, the inherited inability to synthesize cortisol. Severely affected patients carry mutations in the CYB11B1 gene that destroy enzymatic activity. Such patients have signs of androgen excess and usually have hypertension. Mild or non-classic 11 beta-hydroxylase deficiency has been reported previously but not studied genetically. In this study we report analysis of the CYP11B1 genes of three patients thought to suffer from non-classic 11 beta-hydroxylase deficiency. Mutations were detected in the CYP11B1 genes of two patients. One was a compound heterozygote for missense mutations N133H and T319M, whereas the other carried a nonsense mutation (Y423X) on one allele and a missense mutation (P42S) on the other. All three missense mutations affected enzymatic activity when expressed in vitro. No mutations were detected in the coding regions or intron-exon boundaries of the CYP11B1 genes of the other putative non-classic patient. In addition, we were unable to detect CYP11B1 mutations in two hirsute women with mildly elevated levels of 11 beta-hydroxylase precursors who had previously been identified in a screening study of patients in a reproductive endocrinology clinic. We conclude that nonclassic 11 beta-hydroxylase deficiency is a rare disorder. It is not a significant cause of hyperandrogenism in women and relatively stringent criteria should be used to prevent its misdiagnosis.