Homozygous disruption of P450 side-chain cleavage (CYP11A1) is associated with prematurity, complete 46,XY sex reversal, and severe adrenal failure

Effects of exogenous energy on synthesis of steroid hormones and expression characteristics of the CREB/StAR signaling pathway in theca cells of laying hen

Energy and the cAMP-response element binding protein (CREB)/steroidogenic acute regulatory protein (StAR) signaling pathway play important roles in steroid hormone production and follicular development in hens. This present study aimed to investigate the effects of exogenous energy on the synthesis of steroid hormones and the expression characteristics of the CREB/StAR signaling pathway in theca cells of laying hen. The primary theca cells of small yellow follicles were randomly divided into 6 treatments and cultured in medium with glucose concentrations of 1, 1.5, 3, 4.5, 6, and 7.5 mg/mL for 48 h. It was found that growth was robust and cell outlines were clear when cells were cultured with 1, 1.5, 3, and 4.5 mg/mL glucose, but cell viability was diminished and cell density decreased after exposure to glucose at 6 and 7.5 mg/mL for 48 h. Cell viability showed an increasing and then decreasing quadratic response to increasing glucose concentration in culture (r2 = 0.688, P < 0.001). The cell viability of theca cells cultured with 4.5 mg/mL glucose was greater than those cultured with 1, 1.5, 6, and 7.5 mg/mL glucose (P < 0.05). The concentration of estradiol in the medium containing 3 mg/mL glucose was higher than in medium containing 1, 1.5, and 6 mg/mL glucose (P < 0.05). There was an increasing and then decreasing quadratic correlation between progesterone concentrations and glucose concentrations (r2 = 0.522, P = 0.002). The concentration of progesterone in medium with 4.5 mg/mL glucose was higher than in medium with 1 and 7.5 mg/mL glucose (P < 0.05). There was an increasing and then decreasing quadratic correlation between the relative expression of CREB1 (r2 = 0.752, P < 0.001), StAR (r2 = 0.456, P = 0.002), CYP1B1 (r2 = 0.568, P < 0.001), and 3β-HSD (r2 = 0.319, P = 0.018) in theca cells of laying hens and glucose concentrations after treatment with different glucose concentrations for 48 h. After treatment with 4.5 mg/mL glucose, the expression of StAR, CYP1B1, and 3β-HSD genes were increased compared to treatment with 1, 1.5, 3, 6, and 7.5 mg/mL glucose (P < 0.001). There was an increasing and then decreasing quadratic correlation between glucose concentrations and protein expression of CREB1 (r2 = 0.819, P < 0.001), StAR (r2 = 0.844, P < 0.001), 3β-HSD (r2 = 0.801, P < 0.001), and CYP11A1 (r2 = 0.800, P < 0.001) in theca cells of laying hens. The protein expression of CREB1, StAR, and 3β-HSD in theca cells cultured with 4.5 mg/mL glucose was higher than in other groups (P < 0.001). The results indicate that the appropriate glucose concentration (4.5 mg/mL) can improve the synthesis of steroid hormones in theca cells of laying hens through the upregulation of key genes and proteins in the CREB/StAR signaling pathway.

Familial Glucocorticoid Deficiency: the changing landscape of an eponymous syndrome

Familial Glucocorticoid Deficiency encompasses a broad spectrum of monogenic recessive disorders that theoretically solely abrogate cortisol biosynthesis. In reality, delineating clear genotype-phenotype correlations in this disorder is made complicated by marked phenotypic heterogeneity even within kindreds harbouring identical variants. Phenotypes range from isolated glucocorticoid insufficiency to cortisol deficiency plus a variety of superimposed features including salt-wasting and hypoaldosteronism, primary hypothyroidism, hypogonadism and growth defects. Furthermore, mutation type, domain topology and perceived enzyme activity do not always predict disease severity. Given the high burden of disease and implications of a positive diagnosis, genetic testing is crucial in the management of patients warranting detailed delineation of genomic variants including viable functional studies.

Classic genetic and hormonal switches during fetal sex development and beyond

Critical genetic and hormonal switches characterize fetal sex development in humans. They are decisive for gonadal sex determination and subsequent differentiation of the genital and somatic sex phenotype. Only at the first glace these switches seem to behave like the dual 0 and 1 system in computer sciences and lead invariably to either typically male or female phenotypes. More recent data indicate that this model is insufficient. In addition, in case of distinct mutations, many of these switches may act variably, causing a functional continuum of alterations of gene functions and -dosages, enzymatic activities, sex hormone levels, and sex hormone sensitivity, giving rise to a broad clinical spectrum of biological differences of sex development (DSD) and potentially diversity of genital and somatic sex phenotypes. The gonadal anlage is initially a bipotential organ that can develop either into a testis or an ovary. Sex-determining region Y (SRY) is the most important upstream switch of gonadal sex determination inducing SOX9 further downstream, leading to testicular Sertoli cell differentiation and the repression of ovarian pathways. If SRY is absent (virtually "switched off"), e. g., in 46,XX females, RSPO1, WNT4, FOXL2, and other factors repress the male pathway and promote ovarian development. Testosterone and its more potent derivative, dihydrotestosterone (DHT) as well as AMH, are the most important upstream hormonal switches in phenotypic sex differentiation. Masculinization of the genitalia, i. e., external genital midline fusion forming the scrotum, growth of the genital tubercle, and Wolffian duct development, occurs in response to testosterone synthesized by steroidogenic cells in the testis. Müllerian ducts will not develop into a uterus and fallopian tubes in males due to Anti-Müllerian-Hormone (AMH) produced by the Sertoli cells. The functionality of these two hormone-dependent switches is ensured by their corresponding receptors, the intracellular androgen receptor (AR) and the transmembrane AMH type II receptor. The absence of high testosterone and high AMH is crucial for anatomically female genital development during fetal life. Recent technological advances, including single-cell and spatial transcriptomics, will likely shed more light on the nature of these molecular switches.

Genetic Analysis of Pediatric Primary Adrenal Insufficiency of Unknown Etiology: 25 Years' Experience in the UK

CONTEXT

Although primary adrenal insufficiency (PAI) in children and young people is often due to congenital adrenal hyperplasia (CAH) or autoimmunity, other genetic causes occur. The relative prevalence of these conditions is poorly understood.

OBJECTIVE

We investigated genetic causes of PAI in children and young people over a 25 year period.

DESIGN SETTING AND PARTICIPANTS

Unpublished and published data were reviewed for 155 young people in the United Kingdom who underwent genetic analysis for PAI of unknown etiology in three major research centers between 1993 and 2018. We pre-excluded those with CAH, autoimmune, or metabolic causes. We obtained additional data from NR0B1 (DAX-1) clinical testing centers.

INTERVENTION AND OUTCOME MEASUREMENTS

Genetic analysis involved a candidate gene approach (1993 onward) or next generation sequencing (NGS; targeted panels, exomes) (2013-2018).

RESULTS

A genetic diagnosis was reached in 103/155 (66.5%) individuals. In 5 children the adrenal insufficiency resolved and no genetic cause was found. Pathogenic variants occurred in 11 genes: MC2R (adrenocorticotropin receptor; 30/155, 19.4%), NR0B1 (DAX-1; 7.7%), CYP11A1 (7.7%), AAAS (7.1%), NNT (6.5%), MRAP (4.5%), TXNRD2 (4.5%), STAR (3.9%), SAMD9 (3.2%), CDKN1C (1.3%), and NR5A1/steroidogenic factor-1 (SF-1; 0.6%). Additionally, 51 boys had NR0B1 variants identified through clinical testing. Although age at presentation, treatment, ancestral background, and birthweight can provide diagnostic clues, genetic testing was often needed to define the cause.

CONCLUSIONS

PAI in children and young people often has a genetic basis. Establishing the specific etiology can influence management of this lifelong condition. NGS approaches improve the diagnostic yield when many potential candidate genes are involved.

A Novel Intronic Splice-Site Mutation of the CYP11A1 Gene Linked to Adrenal Insufficiency with 46,XY Disorder of Sex Development

A novel CYP11A1: c.1236 + 5G > A was identified, expanding the mutation spectrum of the congenital adrenal insufficiency with 46,XY sex reversal. In a now 17-year-old girl delivered full-term (G2P2, parents unrelated), adrenal failure was diagnosed in the first year of life based on clinical picture of acute adrenal crisis with vomiting, dehydration, weight loss, hypotension, and electrolyte disturbances. At the time, hormonal tests revealed primary adrenocortical insufficiency and steroid profiles showed lack of products of steroidogenesis, and since then the patient has been treated with substitution doses of hydrocortisone and fludrocortisone. At the age of 14, considering the absence of puberty symptoms, extended diagnostic tests revealed elevated LH levels (26.5 mIU/mL) with pre-puberty FSH levels (4.9 mIU/mL), low estradiol (28 pmol/L), testosterone (<2.5 ng/mL), and extremely high levels of ACTH (4961 pg/mL). A cytogenetic study revealed a 46 XY karyotype. A molecular examination confirmed the missense mutation and a novel splice-site mutation of CYP11A1 gene. Compound heterozygosity for the CYP11A1 gene with a known pathogenic variant in one allele and a novel splice site mutation in the second allele is most probably responsible for congenital adrenal insufficiency with 46,XY sex reversal. We discuss the necessity of cytogenetic test in the case of early onset of adrenal failure in the absence of steroidogenesis metabolites in the steroid profile.

Primary Adrenal Insufficiency in Childhood: Data From a Large Nationwide Cohort

CONTEXT

Primary adrenal insufficiency (PAI) is a rare and potentially life-threatening condition that is poorly characterized in children.

OBJECTIVE

To describe causes, presentation, auxological outcome, frequency of adrenal crisis and mortality of a large cohort of children with PAI.

PATIENTS AND METHODS

Data from 803 patients from 8 centers of Pediatric Endocrinology were retrospectively collected.

RESULTS

The following etiologies were reported: 85% (n = 682) congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD); 3.1% (n = 25) X-linked adrenoleukodystrophy; 3.1% (n = 25) autoimmune polyglandular syndrome type 1; 2.5% (n = 20) autoimmune adrenal insufficiency; 2% (n = 16) adrenal hypoplasia congenital; 1.2% (n = 10) non-21-OHD CAH; 1% (n = 8) rare syndromes; 0.6% (n = 5) familial glucocorticoid deficiency; 0.4% (n = 3) acquired adrenal insufficiency; 9 patients (1%) did not receive diagnosis. Since 21-OHD CAH has been extensively characterized, it was not further reviewed. In 121 patients with a diagnosis other than 21-OHD CAH, the most frequent symptoms at diagnosis were fatigue (67%), hyperpigmentation (50.4%), dehydration (33%), and hypotension (31%). Elevated adrenocorticotropic hormone (96.4%) was the most common laboratory finding followed by hyponatremia (55%), hyperkalemia (32.7%), and hypoglycemia (33.7%). The median age at presentation was 6.5 ± 5.1 years (0.1-17.8 years) and the mean duration of symptoms before diagnosis was 5.6 ± 11.6 months (0-56 months) depending on etiology. Rate of adrenal crisis was 2.7 per 100 patient-years. Three patients died from the underlying disease. Adult height, evaluated in 70 patients, was -0.70 ± 1.20 standard deviation score.

CONCLUSIONS

We characterized one of the largest cohorts of children with PAI aiming to improve the knowledge on diagnosis of this rare condition.

Current Insights Into Adrenal Insufficiency in the Newborn and Young Infant

Adrenal insufficiency (AI) is a potentially life-threatening condition that can be difficult to diagnose, especially if it is not considered as a potential cause of a child's clinical presentation or unexpected deterioration. Children who present with AI in early life can have signs of glucocorticoid deficiency (hyperpigmentation, hypoglycemia, prolonged jaundice, poor weight gain), mineralocorticoid deficiency (hypotension, salt loss, collapse), adrenal androgen excess (atypical genitalia), or associated features linked to a specific underlying condition. Here, we provide an overview of causes of childhood AI, with a focus on genetic conditions that present in the first few months of life. Reaching a specific diagnosis can have lifelong implications for focusing management in an individual, and for counseling the family about inheritance and the risk of recurrence.

Clinical and genetic characterization of congenital lipoid adrenal hyperplasia

Disorders of steroid synthesis are a group of anomalies caused by defects in any step of conversion of cholesterol into steroid hormones. The disorders are characterized by defects leading to abnormalities of salt-water balance and/or sexual differentiation. Congenital lipoid adrenal hyperplasia (CLAH) is the most severe form of steroid synthesis disorder caused by the accumulation of cholesterol in the outer mitochondrial membrane due to steroidogenic acute regulatory protein (StAR) deficiency. Pathogenic sequence variants in the gene STAR encoding StAR protein leads to CLAH. In the present study, a Pakistani family was clinically diagnosed with the LAH phenotype. Sanger sequencing of STAR in the family revealed a novel homozygous nonsense mutation [c.295G>T, p.(Glu99*)] in the living affected individual. The study was designed to assist in carrier testing and prenatal diagnosis within the affected family. In addition, searching for common variants in the STAR gene would help in designing low-cost targeted variation testing in other patients.

Long-term outcome of partial P450 side-chain cleavage enzyme deficiency in three brothers: the importance of early diagnosis

OBJECTIVE

CYP11A1 mutations cause P450 side-chain cleavage (scc) deficiency, a rare form of congenital adrenal hyperplasia with a wide clinical spectrum. We detail the phenotype and evolution in a male sibship identified by HaloPlex targeted capture array.

FAMILY STUDY

The youngest of three brothers from a non-consanguineous Scottish family presented with hyperpigmentation at 3.7 years. Investigation showed grossly impaired glucocorticoid function with ACTH elevation, moderately impaired mineralocorticoid function, and normal external genitalia. The older brothers were found to be pigmented also, with glucocorticoid impairment but normal electrolytes. Linkage studies in 2002 showed that all three brothers had inherited the same critical regions of the maternal X chromosome suggesting an X-linked disorder, but analysis of NR0B1 (DAX-1, adrenal hypoplasia) and ABCD1 (adrenoleukodystrophy) were negative. In 2016, next-generation sequencing revealed compound heterozygosity for the rs6161 variant in CYP11A1 (c.940G>A, p.Glu314Lys), together with a severely disruptive frameshift mutation (c.790_802del, K264Lfs*5). The brothers were stable on hydrocortisone and fludrocortisone replacement, testicular volumes (15-20 mL), and serum testosterone levels (24.7, 33.3, and 27.2 nmol/L) were normal, but FSH (41.2 µ/L) was elevated in the proband. The latter had undergone left orchidectomy for suspected malignancy at the age of 25 years and was attending a fertility clinic for oligospermia. Initial histology was reported as showing nodular Leydig cell hyperplasia. However, histological review using CD56 staining confirmed testicular adrenal rest cell tumour (TART).

CONCLUSION

This kinship with partial P450scc deficiency demonstrates the importance of precise diagnosis in primary adrenal insufficiency to ensure appropriate counselling and management, particularly of TART.

Congenital Adrenal Hyperplasias Presenting in the Newborn and Young Infant

Congenital adrenal hyperplasia includes autosomal recessive conditions that affect the adrenal cortex steroidogenic enzymes (cholesterol side-chain cleavage enzyme; 3β-hydroxysteroid dehydrogenase; 17α-hydroxylase/17,20 lyase; P450 oxidoreductase; 21-hydroxylase; and 11β-hydroxylase) and proteins (steroidogenic acute regulatory protein). These are located within the three major pathways of the steroidogenic apparatus involved in the production of mineralocorticoids, glucocorticoids, and androgens. Many countries have introduced newborn screening program (NSP) based on 17-OH-progesterone (17-OHP) immunoassays on dried blood spots, which enable faster diagnosis and treatment of the most severe forms of 21-hydroxylase deficiency (21-OHD). However, in several others, the use of this diagnostic tool has not yet been implemented and clinical diagnosis remains challenging, especially for males. Furthermore, less severe classic forms of 21-OHD and other rarer types of CAHs are not identified by NSP. The aim of this mini review is to highlight both the main clinical characteristics and therapeutic options of these conditions, which may be useful for a differential diagnosis in the neonatal period, while contributing to the biochemical evolution taking place in the steroidogenic field. Currently, chromatographic techniques coupled with tandem mass spectrometry are gaining attention due to an increase in the reliability of the test results of NPS for detecting 21-OHD. Furthermore, the possibility of identifying CAH patients that are not affected by 21-OHD but presenting elevated levels of 17-OHP by NSP and the opportunity to include the recently investigated 11-oxygenated androgens in the steroid profiles are promising tools for a more precise diagnosis and monitoring of some of these conditions.

Primary adrenal insufficiency: New genetic causes and their long-term consequences

Primary adrenal insufficiency (PAI) is a potentially life-threatening condition that requires urgent diagnosis and treatment. Whilst the most common causes are congenital adrenal hyperplasia (CAH) in childhood and autoimmune adrenal insufficiency in adolescence and adulthood, more than 30 other physical and genetics cause of PAI have been reported. Reaching a specific diagnosis can have implications for management and for monitoring associated features, as well as for counselling families about recurrence risk in siblings and relatives. Here, we describe some recent insights into the genetics of adrenal insufficiency and associated molecular mechanisms. We discuss (a) the role of the nuclear receptors DAX-1 (NR0B1) and steroidogenic factor-1 (SF-1, NR5A1) in human adrenal and reproductive dysfunction; (b) multisystem growth restriction syndromes due to gain-of-function in the growth repressors CDKN1C (IMAGE syndrome) and SAMD9 (MIRAGE syndrome), or loss of POLE1; (c) nonclassic forms of STAR and P450scc/CYP11A1 insufficiency that present with a delayed-onset adrenal phenotype and represent a surprisingly prevalent cause of undiagnosed PAI; and (d) a new sphingolipidosis causing PAI due to defects in sphingosine-1-phosphate lyase-1 (SGPL1). Reaching a specific diagnosis can have life-long implications for management. In some situations, milder or nonclassic forms of these conditions can first present in adulthood and may have been labelled, "Addison's disease."

Normal male external genitalia do not rule out CYP11A1 deficiency

Defects in the initial steps of steroidogenesis usually present with female external genitalia in both 46,XX and 46,XY. Hence, they are not often considered in the differential diagnosis of primary adrenal insufficiency children with normal male external genitalia. Here, we report a boy with normal male external genitalia who presented with hyperpigmentation since the age of 2 years but diagnosis was delayed till 11 years of age. Evaluation revealed low-serum cortisol with elevated adrenocorticotropic hormone and direct renin level confirming primary adrenal insufficiency. Clinical exome sequencing analysis revealed a homozygous c.1351C>T (p.R451W) mutation in exon 8 of the CYP11A1 gene which was confirmed on Sanger sequencing. Both parents were heterozygous for the variation. To conclude, we report the first case of CYP11A1 deficiency from India. The report reiterates the existence of non-classic CYP11A1 deficiency characterised by primary adrenal insufficiency and normal male external genitalia in 46,XY.

Translating genomics to the clinical diagnosis of disorders/differences of sex development

The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the complexity of conditions grouped under DSD, genome-wide scanning methods are better suited for identifying disease causing gene variant(s) and providing a clinical diagnosis. Here, we review a number of established genomic tools (karyotyping, chromosomal microarrays and exome sequencing) used in clinic for DSD diagnosis, as well as emerging genomic technologies such as whole-genome (short-read) sequencing, long-read sequencing, and optical mapping used for novel DSD gene discovery. These, together with gene expression and epigenetic studies can potentiate the clinical diagnosis of DSD diagnostic rates and enhance the outcomes for patients and families.

Characterization of the CYP11A1 Nonsynonymous Variant p.E314K in Children Presenting With Adrenal Insufficiency

CONTEXT

Cholesterol side-chain cleavage enzyme (P450scc), encoded by CYP11A1, catalyzes the first step of steroidogenesis. Complete P450scc deficiency leads to primary adrenal insufficiency (PAI) and 46,XY disordered sexual development. Partial impairment can cause variable adrenal and gonadal dysfunction.

OBJECTIVE

Our aim was to evaluate the effects of the CYP11A1 variant p.E314K, identified in patients with PAI, specifically on P450scc enzyme stability and function.

PATIENTS AND METHODS

We studied four boys from two unrelated families presenting with PAI during childhood (3.6 to 9 years old). All patients were compound heterozygous for c.940G>A (p.E314K), a CYP11A1 nonsynonymous variant likely to be pathogenic by some but not all in silico prediction models, and c.835delA (p.I79Yfs*10), a known pathogenic variant. HEK293T cells were transfected with wild type (WT) and p.E314K mutant vectors, and a cycloheximide chase assay was performed to analyze protein stability. Pregnenolone production was assayed from cells expressing WT and p.E314K-F2 fusion proteins.

RESULTS

Two boys experienced spontaneous puberty but then developed evidence of primary gonadal failure at 14 and 18 years old. Two boys had testicular adrenal rest tumor (TART), detected by ultrasound at ages 8.6 and 16 years. Compared with WT, mutant protein synthesis was reduced (P = 0.0006) with increased protein turnover, and mutant P450scc half-life was decreased by ~50%. p.E314K mutant P450scc retained 60% of WT enzymatic activity (P = 0.007).

CONCLUSIONS

The CYP11A1 p.E314K variant impairs P450scc stability and is a possible cause of PAI in childhood. Pathogenic CYP11A1 variants potentially affect both adrenal and gonadal function, and male patients may develop TART.

Predicted Benign and Synonymous Variants in CYP11A1 Cause Primary Adrenal Insufficiency Through Missplicing

Primary adrenal insufficiency (PAI) is a potentially life-threatening condition that can present with nonspecific features and can be difficult to diagnose. We undertook next generation sequencing in a cohort of children and young adults with PAI of unknown etiology from around the world and identified a heterozygous missense variant (rs6161, c.940G>A, p.Glu314Lys) in CYP11A1 in 19 individuals from 13 different families (allele frequency within undiagnosed PAI in our cohort, 0.102 vs 0.0026 in the Genome Aggregation Database; P < 0.0001). Seventeen individuals harbored a second heterozygous rare disruptive variant in CYP11A1 and two had very rare synonymous changes in trans (c.990G>A, Thr330 = ; c.1173C>T, Ser391 =). Although p.Glu314Lys is predicted to be benign and showed no loss-of-function in an Escherichia coli assay system, in silico and in vitro studies revealed that the rs6161/c.940G>A variant, plus the c.990G>A and c.1173C>T changes, affected splicing and that p.Glu314Lys produces a nonfunctional protein in mammalian cells. Taken together, these findings show that compound heterozygosity involving a relatively common and predicted "benign" variant in CYP11A1 is a major contributor to PAI of unknown etiology, especially in European populations. These observations have implications for personalized management and demonstrate how variants that might be overlooked in standard analyses can be pathogenic when combined with other very rare disruptive changes.

Heterozygous mutations in the cholesterol side-chain cleavage enzyme gene (CYP11A1) can cause transient adrenal insufficiency and life-threatening failure to thrive

The first and rate-limited step of steroidogenesis in all steroidogenic tissues is the conversion of cholesterol to pregnenolone, catalysed by P450scc side-chain cleavage enzyme (CYP11A1 gene-SCC). SCC deficiency has been characterised as an autosomal recessive disorder, although it may also be inherited as an autosomal dominant trait in humans. Here, we describe a family of three members carrying the same novel heterozygous CYP11A1 mutation, a c.235G > A missense variant in exon 1: pVal79Ile. A 46 XY boy (P1) was presented at the age of 3 months with early onset adrenal insufficiency and life-threatening failure to thrive, with low adrenal androgens but normal external genitalia. Five years later, the parents had twin girls, one of whom (P2) presented acute adrenal crisis a few hours after birth. The father (P3), born at term, was reported as having suffered from failure to thrive during the neonatal period, though not his only male sibling. This report of severe early adrenal insufficiency caused by a heterozygous mutation of the CYP11A1 gene clearly demonstrates that SCC deficiency may be inherited as an autosomal dominant trait in humans.

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.

Adrenal Insufficiency, Sex Reversal, and Angelman Syndrome due to Uniparental Disomy Unmasking a Mutation in CYP11A1

BACKGROUND/AIMS

Cholesterol side-chain cleavage enzyme (P450scc) deficiency is a rare genetic disorder causing primary adrenal insufficiency with or without a 46,XY disorder of sexual development (DSD). Herein, we report a case of the combination of primary adrenal insufficiency, a DSD (testes with female external genitalia in a setting of a 47,XXY karyotype), and Angelman syndrome.

METHODS

Comprehensive genetic analyses were performed, including a single nucleotide polymorphism microarray and whole-exome sequencing. In vitro studies were performed to evaluate the pathogenicity of the novel mutation that was identified by whole-exome sequencing.

RESULTS

The patient was found to have segmental uniparental disomy (UPD) of chromosome 15 explaining her diagnosis of Angelman syndrome. Whole-exome sequencing further revealed a novel homozygous intronic variant in CYP11A1, the gene encoding P450scc, found within the region of UPD. In vitro studies confirmed that this variant led to decreased efficiency of CYP11A1 splicing.

CONCLUSION

We report the first case of the combination of 2 rare genetic disorders, Angelman syndrome, and P450scc deficiency. After 20 years of diagnostic efforts, significant advances in genetic diagnostic technology allowed us to determine that these 2 disorders originate from a unified genetic etiology, segmental UPD unmasking a novel recessive mutation in CYP11A1.

Aberrant Splicing Is the Pathogenicity Mechanism of the p.Glu314Lys Variant in CYP11A1 Gene

Context: The cholesterol side chain cleavage enzyme (CYP11A1) catalyzes the conversion of cholesterol to pregnenolone, the first rate-limiting step of steroidogenesis. CYP11A1 mutations are associated with primary adrenal insufficiency (PAI) as well as disorders of sex development (DSD) in 46,XY patients. Objective: To define the pathogenicity mechanism for the p.Glu314Lys variant, previously reported, and found in four additional patients with CYP11A1 deficiency. Subjects and Methods: DNA of four patients presenting with delayed PAI and/or 46,XY DSD were studied by Sanger or Massively Parallel sequencing. Three CYP11A1 mutations were characterized in vitro and in silico, and one by mRNA analysis on testicular tissue. Results: All patients were compound heterozygous for the previously described p.Glu314Lys variant. In silico studies predicted this mutation as benign with no effect on splicing but mRNA analysis found that it led to incomplete exon 5 skipping. This mechanism was confirmed by minigene experiment. The protein carrying this mutation without exon skipping should conserve almost normal activity, according to in vitro studies. Two other mutations found in trans, the p.Arg120Gln and p.Arg465Trp, had similar activity compared to negative control, consistent with the in silico studies. Conclusions: We provide biological proof that the p. Glu314Lys variant is pathogenic due to its impact on splicing and seems responsible for the moderate phenotype of the four patients reported herein. The present study highlights the importance of considering the potential effect of a missense variant on splicing when it is not predicted to be disease causing.

A novel splice site variant in CYP11A1 in trans with the p.E314K variant in a male patient with congenital adrenal insufficiency

BACKGROUND

The CYP11A1 gene encodes the cytochrome P450 side-chain cleavage enzyme, which is essential for steroid formation. Recessive variants in this gene can lead to impairment of sexual differentiation caused by a complete or partial loss of steroid hormone production. The phenotypic spectrum in affected 46XY males may vary from surgically repairable defects including cryptorchidism and hypospadias to complete feminization of external gonads, accompanied by symptoms of adrenal dysfunction.

METHODS

Whole-exome sequencing (WES) of a 12-year-old male proband and his parents was performed after a protracted diagnostic odyssey failed to uncover the cause of his primary adrenal insufficiency. Of note, the proband had early symptomatology and corrective surgery for hypospadias, raising suspicion for a disorder of steroidogenesis.

RESULTS

WES identified compound heterozygous variants in CYP11A1 including a novel canonical splice site variant (c.425+1G>A) and a previously reported p.E314K variant, which were consistent with a diagnosis of congenital adrenal insufficiency with partial 46XY sex reversal.

CONCLUSION

Congenital adrenal insufficiency with 46XY sex reversal is a rare disorder that is characterized by dysregulation of steroid hormone synthesis, leading to adrenal and gonadal dysfunction. In this report, we describe a patient with adrenal insufficiency, hypospadias, and skin hyperpigmentation who was found to have a novel c.425+1G>A variant in trans with the p.E314K variant in CYP11A1. We performed structural analyses to examine the effect of the p.E314K variant on protein function and show that it falls in the core of the protein may disrupt cholesterol binding in the active site.

Disorders in the initial steps of steroid hormone synthesis

Steroidogenesis begins with cellular internalization of low-density lipoprotein particles and subsequent intracellular processing of cholesterol. Disorders in these steps include Adrenoleukodystrophy, Wolman Disease and its milder variant Cholesterol Ester Storage Disease, and Niemann-Pick Type C Disease, all of which may present with adrenal insufficiency. The means by which cholesterol is directed to steroidogenic mitochondria remains incompletely understood. Once cholesterol reaches the outer mitochondrial membrane, its delivery to the inner mitochondrial membrane is regulated by the steroidogenic acute regulatory protein (StAR). Severe StAR mutations cause classic congenital lipoid adrenal hyperplasia, characterized by lipid accumulation in the adrenal, adrenal insufficiency, and disordered sexual development in 46,XY individuals. The lipoid CAH phenotype, including spontaneous puberty in 46,XX females, is explained by a two-hit model. StAR mutations that retain partial function cause a milder, non-classic disease characterized by glucocorticoid deficiency, with lesser disorders of mineralocorticoid and sex steroid synthesis. Once inside the mitochondria, cholesterol is converted to pregnenolone by the cholesterol side-chain cleavage enzyme, P450scc, encoded by the CYP11A1 gene. Rare patients with mutations of P450scc are clinically and hormonally indistinguishable from those with lipoid CAH, and may also present as milder non-classic disease. Patients with P450scc defects do not have the massive adrenal hyperplasia that characterizes lipoid CAH, but adrenal imaging may occasionally fail to distinguish these, necessitating DNA sequencing.

Thirty-Eight-Year Follow-Up of Two Sibling Lipoid Congenital Adrenal Hyperplasia Patients Due to Homozygous Steroidogenic Acute Regulatory (STARD1) Protein Mutation. Molecular Structure and Modeling of the STARD1 L275P Mutation

Objective: Review the impact of StAR (STARD1) mutations on steroidogenesis and fertility in LCAH patients. Examine the endocrine mechanisms underlying the pathology of the disorder and the appropriate therapy for promoting fertility and pregnancies.

Design: Published data in the literature and a detailed 38-year follow-up of two sibling LCAH patients. Molecular structure and modeling of the STARD1 L275P mutation.

Setting: University hospital.

Patients: Patient A (46,XY female phenotype) and patient B (46,XX female) with LCAH bearing the L275P mutation in STARD1.

Interventions: Since early-age diagnosis, both patients underwent corticoid replacement therapy. Patient A received estrogen therapy at pubertal age. Clomiphene therapy was given to Patient B to induce ovulation. Pregnancies were protected with progesterone administration.

Main Outcome Measures: Clinical and molecular assessment of adrenal and gonadal functions.

Results: Both patients have classic manifestations of corticosteroid deficiency observed in LCAH. Time of onset and severity were different. Patient A developed into a female phenotype due to early and severe damage of Leydig cells. Patient B started a progressive pubertal development, menarche and regular non-ovulatory cycle. She was able to have successful pregnancies.

Conclusions: Understanding the molecular structure and function of STARD1 in all steroidogenic tissues is the key for comprehending the heterogeneous clinical manifestations of LCAH, and the development of an appropriate strategy for the induction of ovulation and protecting pregnancies in this disease.

First case report of rare congenital adrenal insufficiency caused by mutations in the CYP11A1 gene in the Czech Republic

We characterized a case of congenital adrenal insufficiency caused by cholesterol side-chain cleavage enzyme (P450scc) deficiency. The patient presented after birth with cardiopulmonary instability, hyponatremia, hyperkalemia, hypoglycemia and metabolic acidosis. We confirmed primary adrenal insufficiency. There were no signs of the external genitalia virilism. The replacement therapy with glucocorticoids and mineralocorticoids led to normal laboratory results. At the age of 12 years, we confirmed hypergonadotropic hypogonadism, which revealed disorder of steroidogenesis in the adrenal glands and in the gonads. The enzymatic block was found at the beginning of steroidogenesis. The mutation was confirmed in the CYP11A1 gene. The patient is compound heterozygote for the novel CYP11A1 missense mutation c.412G>A (p.Gly138Arg) in exon 2 and frameshift mutation c.508_509delCT (p.Leu170Valfs*30) in exon 3. The CYP11A1: c.412G>A (p.Gly138Arg) was predicted as pathogenic by in silico analysis. So far, only 19 patients with CYP11A1 mutations causing P450scc deficiency have been reported worldwide. There are no related reports in the Czech Republic.

Evolution of steroids during pregnancy: Maternal, placental and fetal synthesis

Progesterone, estrogens, androgens and glucocorticoids are involved in pregnancy from implantation to parturition. Their biosynthesis and their metabolism result from complex pathways involving the fetus, the placenta and the mother. The absence of expression of some steroïdogenic enzymes as CYP17 in placenta and in adrenal fetal zone and the better determination of the onset and variation of others especially HSD3B2 during the pregnancy explain the production of the steroid hormones. Moreover the consequences of some disorders of steroidogenesis (especially aromatase, POR, CYP11A1 and 21-hydroxylase deficiencies) in fetus and mother during the pregnancy have permit to elucidate these complex pathways. This better knowledge of steroid hormones production associated with their dosages in maternal plasma/urine or amniotic fluid using new specific assays as LC-MS MS could facilitate the follow-up of normal and pathological pregnancies. Moreover, these advances should be a basis to evaluate the impact of multiple pathologies of the pregnancy and pharmacologic and xenobiotic consequences on their metabolism.

Hereditary truncating mutations of DNA repair and other genes in BRCA1/BRCA2/PALB2-negatively tested breast cancer patients

Hereditary breast cancer comprises a minor but clinically meaningful breast cancer (BC) subgroup. Mutations in the major BC-susceptibility genes are important prognostic and predictive markers; however, their carriers represent only 25% of high-risk BC patients. To further characterize variants influencing BC risk, we performed SOLiD sequencing of 581 genes in 325 BC patients (negatively tested in previous BRCA1/BRCA2/PALB2 analyses). In 105 (32%) patients, we identified and confirmed 127 truncating variants (89 unique; nonsense, frameshift indels, and splice site), 19 patients harbored more than one truncation. Forty-six (36 unique) truncating variants in 25 DNA repair genes were found in 41 (12%) patients, including 16 variants in the Fanconi anemia (FA) genes. The most frequent variant in FA genes was c.1096_1099dupATTA in FANCL that also show a borderline association with increased BC risk in subsequent analysis of enlarged groups of BC patients and controls. Another 81 (53 unique) truncating variants were identified in 48 non-DNA repair genes in 74 patients (23%) including 16 patients carrying variants in genes coding proteins of estrogen metabolism/signaling. Our results highlight the importance of mutations in the FA genes' family, and indicate that estrogen metabolism genes may reveal a novel candidate genetic component for BC susceptibility.

Rare Causes of Primary Adrenal Insufficiency: Genetic and Clinical Characterization of a Large Nationwide Cohort

CONTEXT

Primary adrenal insufficiency (PAI) is a life-threatening condition that is often due to monogenic causes in children. Although congenital adrenal hyperplasia occurs commonly, several other important molecular causes have been reported, often with overlapping clinical and biochemical features. The relative prevalence of these conditions is not known, but making a specific diagnosis can have important implications for management.

OBJECTIVE

The objective of the study was to investigate the clinical and molecular genetic characteristics of a nationwide cohort of children with PAI of unknown etiology.

DESIGN

A structured questionnaire was used to evaluate clinical, biochemical, and imaging data. Genetic analysis was performed using Haloplex capture and next-generation sequencing. Patients with congenital adrenal hyperplasia, adrenoleukodystrophy, autoimmune adrenal insufficiency, or obvious syndromic PAI were excluded.

SETTING

The study was conducted in 19 tertiary pediatric endocrinology clinics.

PATIENTS

Ninety-five children (48 females, aged 0-18 y, eight familial) with PAI of unknown etiology participated in the study.

RESULTS

A genetic diagnosis was obtained in 77 patients (81%). The range of etiologies was as follows: MC2R (n = 25), NR0B1 (n = 12), STAR (n = 11), CYP11A1 (n = 9), MRAP (n = 9), NNT (n = 7), ABCD1 (n = 2), NR5A1 (n = 1), and AAAS (n = 1). Recurrent mutations occurred in several genes, such as c.560delT in MC2R, p.R451W in CYP11A1, and c.IVS3ds+1delG in MRAP. Several important clinical and molecular insights emerged.

CONCLUSION

This is the largest nationwide study of the molecular genetics of childhood PAI undertaken. Achieving a molecular diagnosis in more than 80% of children has important translational impact for counseling families, presymptomatic diagnosis, personalized treatment (eg, mineralocorticoid replacement), predicting comorbidities (eg, neurological, puberty/fertility), and targeting clinical genetic testing in the future.

Clinical and molecular review of atypical 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 mutations in the genes encoding for steroidogenic enzymes that involved cortisol synthesis. More than 90% of cases are caused by a defect in the enzyme 21-hydroxylase. Four other enzyme deficiencies (cholesterol side-chain cleavage, 17α-hydroxylase [P450c17], 11β-hydroxylase [P450c11β], 3β-hydroxysteroid dehydrogenase) in the steroid biosynthesis pathway, along with one cholesterol transport protein defect (steroidogenic acute regulatory protein), and one electrontransfer protein (P450 oxidoreductase) account for the remaining cases. The clinical symptoms of the different forms of CAH result from the particular hormones that are deficient and those that are produced in excess. A characteristic feature of CAH is genital ambiguity or disordered sex development, and most variants are associated with glucocorticoid deficiency. However, in the rare forms of CAH other than 21-hydroxylase deficiency so-called "atypical CAH", the clinical and hormonal phenotypes can be more complicated, and are not well recognized. This review will focus on the atypical forms of CAH, including the genetic analyses, and phenotypic correlates.

Rare diseases in clinical endocrinology: a taxonomic classification system

PURPOSE

Rare endocrine-metabolic diseases (REMD) represent an important area in the field of medicine and pharmacology. The rare diseases of interest to endocrinologists involve all fields of endocrinology, including rare diseases of the pituitary, thyroid and adrenal glands, paraganglia, ovary and testis, disorders of bone and mineral metabolism, energy and lipid metabolism, water metabolism, and syndromes with possible involvement of multiple endocrine glands, and neuroendocrine tumors. Taking advantage of the constitution of a study group on REMD within the Italian Society of Endocrinology, consisting of basic and clinical scientists, a document on the taxonomy of REMD has been produced.

METHODS AND RESULTS

This document has been designed to include mainly REMD manifesting or persisting into adulthood. The taxonomy of REMD of the adult comprises a total of 166 main disorders, 338 including all variants and subtypes, described into 11 tables.

CONCLUSIONS

This report provides a complete taxonomy to classify REMD of the adult. In the future, the creation of registries of rare endocrine diseases to collect data on cohorts of patients and the development of common and standardized diagnostic and therapeutic pathways for each rare endocrine disease is advisable. This will help planning and performing intervention studies in larger groups of patients to prove the efficacy, effectiveness, and safety of a specific treatment.

Whole-Exome Sequencing in the Differential Diagnosis of Primary Adrenal Insufficiency in Children

Adrenal insufficiency is a rare, but potentially fatal medical condition. In children, the cause is most commonly congenital and in recent years a growing number of causative gene mutations have been identified resulting in a myriad of syndromes that share adrenal insufficiency as one of the main characteristics. The evolution of adrenal insufficiency is dependent on the variant and the particular gene affected, meaning that rapid and accurate diagnosis is imperative for effective treatment of the patient. Common practice is for candidate genes to be sequenced individually, which is a time-consuming process and complicated by overlapping clinical phenotypes. However, with the availability, and increasing cost effectiveness of whole-exome sequencing, there is the potential for this to become a powerful diagnostic tool. Here, we report the results of whole-exome sequencing of 43 patients referred to us with a diagnosis of familial glucocorticoid deficiency (FGD) who were mutation negative for MC2R, MRAP, and STAR the most commonly mutated genes in FGD. WES provided a rapid genetic diagnosis in 17/43 sequenced patients, for the remaining 60% the gene defect may be within intronic/regulatory regions not covered by WES or may be in gene(s) representing novel etiologies. The diagnosis of isolated or familial glucocorticoid deficiency was only confirmed in 3 of the 17 patients, other genetic diagnoses were adrenal hypo- and hyperplasia, Triple A, and autoimmune polyendocrinopathy syndrome type I, emphasizing both the difficulty of phenotypically distinguishing between disorders of PAI and the utility of WES as a tool to achieve this.

Congenital lipoid adrenal hyperplasia

Congenital lipoid adrenal hyperplasia (lipoid CAH) is the most fatal form of CAH, as it disrupts adrenal and gonadal steroidogenesis. Most cases of lipoid CAH are caused by recessive mutations in the gene encoding steroidogenic acute regulatory protein (StAR). Affected patients typically present with signs of severe adrenal failure in early infancy and 46,XY genetic males are phenotypic females due to disrupted testicular androgen secretion. The StAR p.Q258X mutation accounts for about 70% of affected alleles in most patients of Japanese and Korean ancestry. However, it is more prevalent (92.3%) in the Korean population. Recently, some patients have been showed that they had late and mild clinical findings. These cases and studies constitute a new entity of 'nonclassic lipoid CAH'. The cholesterol side-chain cleavage enzyme, P450scc (CYP11A1), plays an essential role converting cholesterol to pregnenolone. Although progesterone production from the fetally derived placenta is necessary to maintain a pregnancy to term, some patients with P450scc mutations have recently been reported. P450scc mutations can also cause lipoid CAH and establish a recently recognized human endocrine disorder.

Revisiting the roles of progesterone and allopregnanolone in the nervous system: resurgence of the progesterone receptors

Progesterone is commonly considered as a female reproductive hormone and is well-known for its role in pregnancy. It is less well appreciated that progesterone and its metabolite allopregnanolone are also male hormones, as they are produced in both sexes by the adrenal glands. In addition, they are synthesized within the nervous system. Progesterone and allopregnanolone are associated with adaptation to stress, and increased production of progesterone within the brain may be part of the response of neural cells to injury. Progesterone receptors (PR) are widely distributed throughout the brain, but their study has been mainly limited to the hypothalamus and reproductive functions, and the extra-hypothalamic receptors have been neglected. This lack of information about brain functions of PR is unexpected, as the protective and trophic effects of progesterone are much investigated, and as the therapeutic potential of progesterone as a neuroprotective and promyelinating agent is currently being assessed in clinical trials. The little attention devoted to the brain functions of PR may relate to the widely accepted assumption that non-reproductive actions of progesterone may be mainly mediated by allopregnanolone, which does not bind to PR, but acts as a potent positive modulator of γ-aminobutyric acid type A (GABA(A) receptors. The aim of this review is to critically discuss effects of progesterone on the nervous system via PR, and of allopregnanolone via its modulation of GABA(A) receptors, with main focus on the brain.

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.

Identification of novel mutations in STAR gene in patients with lipoid congenital adrenal hyperplasia: a first report from India

Lipoid congenital adrenal hyperplasia (LCAH), a rare disorder of steroid biosynthesis, is the most severe form of CAH. We report novel molecular findings of three unrelated infants with LCAH diagnosed at our center. A known missense mutation c.653C>T (p.A218V) and two novel mutations [premature termination c.441G>A (or p.W147X) and frameshift deletion c.del815G (or p.R272PfsX35)] were identified after complete sequencing of the STAR gene. Prenatal diagnosis was carried out for the family with mutation c.815delG by molecular testing wherein the fetus was found to be homozygous for the mutation. This is the first report of molecular diagnosis and prenatal testing for LCAH from India.

Distinguishing deficiencies in the steroidogenic acute regulatory protein and the cholesterol side chain cleavage enzyme causing neonatal adrenal failure

OBJECTIVES

To determine the genetic basis of disordered steroidogenesis in Kuwaiti siblings.

STUDY DESIGN

Two siblings (46,XX and 46,XY) had normal female external genitalia and severe glucocorticoid and mineralocorticoid deficiency presenting in the first month of life. Abdominal ultrasonography showed normal size adrenal glands, suggesting cholesterol side chain cleavage enzyme (P450scc) deficiency. The CYP11A1 gene encoding P450scc and the STAR gene encoding the steroidogenic acute regulatory protein (StAR) were directly sequenced from leukocyte DNA.

RESULTS

All exons and intron/exon boundaries of the CYP11A1 gene were normal; the STAR gene was homozygous for a novel 14-base deletion/frameshift in exon 4 (g.4643_4656del), so that no functional protein could be produced. Both parents and an unaffected sibling were heterozygous; zygosity was confirmed with a BsmF1 restriction fragment length polymorphism.

CONCLUSIONS

Unlike most patients with StAR deficiency, our patients did not have the massive adrenal hyperplasia typical of congenital lipoid adrenal hyperplasia. The distinction between StAR and P450scc deficiency may require gene sequencing.

Varied clinical presentations of seven patients with mutations in CYP11A1 encoding the cholesterol side-chain cleavage enzyme, P450scc

CONTEXT

The cholesterol side-chain cleavage enzyme P450scc, encoded by CYP11A1, converts cholesterol to pregnenolone to initiate steroidogenesis. P450scc deficiency can disrupt adrenal and gonadal steroidogenesis, resembling congenital lipoid adrenal hyperplasia clinically and hormonally; only 12 such patients have been reported previously.

OBJECTIVE

We sought to expand clinical and genetic experience with P450scc deficiency.

PATIENTS AND METHODS

We sequenced candidate genes in 7 children with adrenal insufficiency who lacked disordered sexual development. P450scc missense mutations were recreated in the F2 vector, which expresses the fusion protein P450scc-Ferredoxin Reductase-Ferredoxin. COS-1 cells were transfected, production of pregnenolone was assayed, and apparent kinetic parameters were calculated. Previously described P450scc mutants were assayed in parallel.

RESULTS

Four of five Bedouin children in one kindred were compound heterozygotes for mutations c.694C>T (Arg232Stop) and c.644T>C (Phe215Ser). Single-nucleotide polymorphism analysis confirmed segregation of these mutations. The fifth kindred member and another Bedouin patient presented in infancy and were homozygous for Arg232Stop. A patient from Fiji presenting in infancy was homozygous for c.358T>C (Arg120Stop). All mutations are novel. As assayed in the F2 fusion protein, P450scc Phe215Ser retained 2.5% of wild-type activity; previously described mutants Leu141Trp and Ala269Val had 2.6% and 12% of wild-type activity, respectively, and Val415Glu and c.835delA lacked detectable activity.

CONCLUSIONS

Although P450scc is required to produce placental progesterone required to maintain pregnancy, severe mutations in P450scc are compatible with term gestation; milder P450scc mutations may present later without disordered sexual development. Enlarged adrenals usually distinguish steroidogenic acute regulatory protein deficiency from P450scc deficiency, but only DNA sequencing is definitive.

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.

Delayed diagnosis of adrenal insufficiency in a patient with severe penoscrotal hypospadias due to two novel P450 side-change cleavage enzyme (CYP11A1) mutations (p.R360W; p.R405X)

CONTEXT

Cytochrome P450 side-chain cleavage enzyme (CYP11A1) catalyses the first and rate-limiting step of steroidogenesis, the conversion of cholesterol to pregnenolone. CYP11A1 deficiency is commonly associated with adrenal insufficiency, and in 46,XY individuals, with variable degrees of disorder of sex development (DSD).

PATIENT AND METHODS

The patient was born with hyperpigmentation, micropenis, penoscrotal hypospadias, and mild cryptorchidism. Biochemical and hormonal findings were normal except for low testosterone and low-borderline cortisol. However, no short synacthen test was undertaken. Development was unremarkable apart from an episode labeled as sepsis with documented hyperkalemia and elevated C-reactive protein at age 15 days. Diagnosis of 46,XY DSD was made at age 2.5 months. Progression of hyperpigmentation prompted further investigations and the diagnosis of adrenal insufficiency was established at 2 years with raised ACTH, normal renin activity, and failure of cortisol to respond to short synacthen test. Genetic analyses were performed. The novel CYP11A1 mutations were characterized in vitro and in silico.

RESULTS

The patient was compound heterozygous for two novel CYP11A1 mutations, p.R360W and p.R405X. p.R360W retained 30-40% of wild-type activity. In silico analyses confirmed these findings and indicated that p.R405X is severe.

CONCLUSIONS

This study demonstrates the pathogenicity of two novel CYP11A1 mutations found in a patient with delayed diagnosis of CYP11A1 deficiency. Patients with partial deficiencies of steroidogenic enzymes are at risk to be misdiagnosed if adrenal function is not assessed. The adrenocortical function should be routinely assessed in all patients with DSD including severe hypospadias of unknown origin to prevent life-threatening adrenal crises.

Fetal glucocorticoid synthesis is required for development of fetal adrenal medulla and hypothalamus feedback suppression

During pregnancy, fetal glucocorticoid is derived from both maternal supply and fetal secretion. We have created mice with a disruption of the Cyp11a1 gene resulting in loss of fetal steroid secretion but preserving the maternal supply. Cyp11a1null embryos have appreciable although lower amounts of circulating corticosterone, the major mouse glucocorticoid, suggesting that transplacental corticosterone is a major source of corticosterone in fetal circulation. These embryos thus provide a means to examine the effect of fetal glucocorticoids. The adrenal in Cyp11a1 null embryos was disorganized with abnormal mitochondria and oil accumulation. The adrenal medullary cells did not express phenylethanolamine N-methyltransferase and synthesized no epinephrine. Cyp11a1 null embryos had decreased diencephalon Hsd11b1, increased diencephalon Crh, and increased pituitary Pomc expression, leading to higher adrenocorticotropin level in the plasma. These data indicate blunted feedback suppression despite reasonable amounts of circulating corticosterone. Thus, the corticosterone synthesized in situ by the fetus is required for negative feedback suppression of the hypothalamus-pituitary-adrenal axis and for catecholamine synthesis in adrenal medulla.

Congenital lipoid adrenal hyperplasia (a rare form of adrenal insufficiency and ambiguous genitalia) caused by a novel mutation of the steroidogenic acute regulatory protein gene

Congenital lipoid adrenal hyperplasia (lipoid CAH) is a rare autosomal recessive disorder of adrenal and gonadal steroidogenesis. It is most frequently caused by mutations in the steroidogenic acute regulatory protein (StAR) gene. Patients with lipoid CAH typically present with adrenal crisis in early infancy, and those with a 46,XY karyotype have female genitalia. However, it has been recently recognized that the phenotype can be quite variable, in that adrenal insufficiency is detected later in life and patients may have partially masculinized or even normal male genitalia. We report a patient assigned and reared as a female with a 46,XY karyotype and with a homozygous intron 2 (c.178+1G>C) splice site mutation of the StAR gene, which is a novel mutation that causes lipoid CAH. Her clinical presentation was somewhat atypical for a patient with classic lipoid CAH, marked by mild masculinization of the genitalia, detectable adrenal steroids at baseline, and ability to tolerate the stress of a surgical procedure with anesthesia without receiving glucocorticoid treatment.

CONCLUSION

There is significant phenotypic variability among patients with lipoid CAH. While splice site mutations in the StAR gene lead to premature translational termination, resulting in truncated and non-functional proteins, there is phenotypic variability among patients with such mutations. Our patient appears to have the more atypical phenotype compared to reported patients with similar mutations. The molecular mechanism underlying this heterogeneity remains unclear.

Steroidogenic factor 1 and the central nervous system

Steroidogenic factor 1 (SF-1; officially designated NR5a1) is a member of a nuclear receptor superfamily with important roles in the development of endocrine systems. Studies with global and tissue-specific (i.e. central nervous system) knockout mice have revealed several roles of SF-1 in brain. These include morphological effects on the development of the ventromedial nucleus of the hypothalamus and functional effects on body weight regulation through modulation of physical activity, anxiety-like behaviours and female sexual behaviours. Although such defects are almost certainly a result of the absence of SF-1 acting as a transcription factor in the hypothalamus, global SF-1 knockout mice also represent a model for studying the sex differences in the brain that develop in the absence of exposure to foetal sex steroid hormones as a result of the absence of gonads. In the present review, current knowledge of the roles of SF-1 protein in the central nervous system is discussed.

Features of the retinal environment which affect the activities and product profile of cholesterol-metabolizing cytochromes P450 CYP27A1 and CYP11A1

The retina is the sensory organ in the back of the eye which absorbs and converts light to electrochemical impulses transferred to the brain. Herein, we studied how retinal environment affects enzyme-mediated cholesterol removal. We focused on two mitochondrial cytochrome P450 enzymes, CYPs 27A1 and 11A1, which catalyze the first steps in metabolism of cholesterol in the retina and other tissues. Phospholipids (PL) from mitochondria of bovine neural retina, retinal pigment epithelium, liver and adrenal cortex were isolated and compared for the effect on kinetic properties of purified recombinant CYPs in the reconstituted system in vitro. The four studied tissues were also evaluated for the mitochondrial PL and cholesterol content and levels of CYPs 27A1, 11A1 and their redox partners. The data obtained were used for modeling the retinal environment in the in vitro enzyme assays in which we detected the P450 metabolites, 22R-hydroxycholesterol and 5-cholestenoic acid, unexpectedly found by us in the retina in our previous studies. The effect of the by-product of the visual cycle pyridinium bis-retinoid A2E on kinetics of CYP27A1-mediated cholesterol metabolism was also investigated. The results provide insight into the retina's regulation of the enzyme-mediated cholesterol removal.

Early steps in steroidogenesis: intracellular cholesterol trafficking

Steroid hormones are made from cholesterol, primarily derived from lipoproteins that enter cells via receptor-mediated endocytosis. In endo-lysosomes, cholesterol is released from cholesterol esters by lysosomal acid lipase (LAL; disordered in Wolman disease) and exported via Niemann-Pick type C (NPC) proteins (disordered in NPC disease). These diseases are characterized by accumulated cholesterol and cholesterol esters in most cell types. Mechanisms for trans-cytoplasmic cholesterol transport, membrane insertion, and retrieval from membranes are less clear. Cholesterol esters and "free" cholesterol are enzymatically interconverted in lipid droplets. Cholesterol transport to the cholesterol-poor outer mitochondrial membrane (OMM) appears to involve cholesterol transport proteins. Cytochrome P450scc (CYP11A1) then initiates steroidogenesis by converting cholesterol to pregnenolone on the inner mitochondrial membrane (IMM). Acute steroidogenic responses are regulated by cholesterol delivery from OMM to IMM, triggered by the steroidogenic acute regulatory protein (StAR). Chronic steroidogenic capacity is determined by CYP11A1 gene transcription. StAR mutations cause congenital lipoid adrenal hyperplasia, with absent steroidogenesis, potentially lethal salt loss, and 46,XY sex reversal. StAR mutations initially destroy most, but not all steroidogenesis; low levels of StAR-independent steroidogenesis are lost later due to cellular damage, explaining the clinical findings. Rare P450scc mutations cause a similar syndrome. This review addresses these early steps in steroid biosynthesis.

Disorders of sex development

Infants born with ambiguous genitalia represent a complex clinical challenge. A systematic clinical investigation aims at determining the hormone production and which anatomical structures are present in order to understand at what level the sex differentiation has been affected; chromosomal, gonadal or hormonal synthesis and action levels. The increased genetic knowledge in the field has opened up new diagnostic possibilities. Sex development requires the balanced and sequential activation of transcription factors, signaling molecules and hormones. It has recently been shown that not only testis but also normal ovarian development is an active process. Genes involved in gonadal disorders of sex development often act in a gene dosage-dependent manner, with different effects in XY or XX embryos. The management of patients with disorders of sex development, including decisions about sex of rearing, must be carried out by a specialized multidisciplinary team and include an extended genetic investigation as well as psychological considerations.

Partial defect in the cholesterol side-chain cleavage enzyme P450scc (CYP11A1) resembling nonclassic congenital lipoid adrenal hyperplasia

CONTEXT

The cholesterol side-chain cleavage enzyme (P450scc), encoded by the CYP11A1 gene, converts cholesterol to pregnenolone to initiate steroidogenesis. Genetic defects in P450scc cause a rare autosomal recessive disorder that is clinically indistinguishable from congenital lipoid adrenal hyperplasia (lipoid CAH). Nonclassic lipoid CAH is a recently recognized disorder caused by mutations in the steroidogenic acute regulatory protein (StAR) that retain partial function.

OBJECTIVE

We describe two siblings with hormonal findings suggesting nonclassic lipoid CAH, who had a P450scc mutation that retains partial function.

PATIENTS AND METHODS

A 46,XY male presented with underdeveloped genitalia and partial adrenal insufficiency; his 46,XX sister presented with adrenal insufficiency. Hormonal studies suggested nonclassic lipoid CAH. Sequencing of the StAR gene was normal, but compound heterozygous mutations were found in the CYP11A1 gene. Mutations were recreated in the F2 plasmid expressing a fusion protein of the cholesterol side-chain cleavage system. P450scc activity was measured as Vmax/Km for pregnenolone production in transfected COS-1 cells.

RESULTS

The patients were compound heterozygous for the previously described frameshift mutation 835delA and the novel missense mutation A269V. When expressed in the P450scc moiety of F2, the A269V mutant retained 11% activity of the wild-type F2 protein.

CONCLUSIONS

There is a broad clinical spectrum of P450scc deficiency. Partial loss-of-function CYP11A1 mutation can present with a hormonal phenotype indistinguishable from nonclassic lipoid CAH.

The molecular biology, biochemistry, and physiology of human steroidogenesis and its disorders

Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.

Adrenodoxin: the archetype of vertebrate-type [2Fe-2S] cluster ferredoxins

Adrenodoxin is probably the best characterized member of the vertebrate-type [2Fe-2S]-cluster ferredoxins. It has been in the spotlight of scientific interest for many years due to its essential role in mammalian steroid hormone biosynthesis, where it acts as electron mediator between the NADPH-dependent adrenodoxin reductase and several mitochondrial cytochromes P450. In this review we will focus on the present knowledge about protein-protein recognition in the mitochondrial cytochrome P450 system and the modulation of the electron transfer between Adx and its redox partners, AdR and CYP(s). We also intend to point out the potential biotechnological applications of Adx as a versatile electron donor to different cytochromes P450, both in vitro and in vivo. Finally we will address the comparison between the mammalian cytochrome P450-associated adrenodoxin and ferredoxins involved in iron-sulfur-cluster biosynthesis. Despite their different functions, these proteins display an amazing similarity regarding their primary sequence, tertiary structure and biophysical features.

46,XY DSD due to impaired androgen production

Disorders of androgen production can occur in all steps of testosterone biosynthesis and secretion carried out by the foetal Leydig cells as well as in the conversion of testosterone into dihydrotestosterone (DHT). The differentiation of Leydig cells from mesenchymal cells is the first walk for testosterone production. In 46,XY disorders of sex development (DSDs) due to Leydig cell hypoplasia, there is a failure in intrauterine and postnatal virilisation due to the paucity of interstitial Leydig cells to secrete testosterone. Enzymatic defects which impair the normal synthesis of testosterone from cholesterol and the conversion of testosterone to its active metabolite DHT are other causes of DSD due to impaired androgen production. Mutations in the genes that codify the enzymes acting in the steps from cholesterol to DHT have been identified in affected patients. Patients with 46,XY DSD secondary to defects in androgen production show a variable phenotype, strongly depending of the specific mutated gene. Often, these conditions are detected at birth due to the ambiguity of external genitalia but, in several patients, the extremely undervirilised genitalia postpone the diagnosis until late childhood or even adulthood. These patients should receive long-term care provided by multidisciplinary teams with experience in this clinical management.

Diagnosis of diseases of steroid hormone production, metabolism and action

Biochemical tests have been the basis for investigations of disorders affecting steroid hormones. In recent years it has been possible however to study the genes that determine functional enzymes, cofactors, receptors, transcription factors and signaling systems that are involved in the process. Analyses of mutations are available as a diagnostic service for only a few of these genes although research laboratories may be able to provide a service. Both biochemical and genetic research have brought to light new disorders. Some genes for transcription factors involved in the development of the endocrine organs have also been identified and patients with defects in these processes have been found. This paper will review general aspects of adrenal disorders with emphasis on clinical and laboratory findings. As with all endocrine investigations there are few single measurements that provide a definitive answer to a diagnosis. Timing of samples in relation to age, gender and time of day needs to be considered.

A novel homozygous mutation in CYP11A1 gene is associated with late-onset adrenal insufficiency and hypospadias in a 46,XY patient

CONTEXT

The first and the rate-limiting step in the biosynthesis of hormones in all steroidogenic tissues, conversion of cholesterol to pregnenolone, is catalyzed by the cholesterol side-change cleavage cytochrome P450 (P450scc) encoded by a single gene, CYP11A1. To date, mutations in CYP11A1 gene have been reported in six patients, all of whom presented with adrenal insufficiency within the first 4 yr of life and severely underandrogenized external genitalia (Prader stages 1-2).

OBJECTIVE

Our aim was to characterize in vitro and in vivo effects of a novel homozygous CYP11A1 gene mutation identified in a patient with an unusual presentation of P450scc deficiency.

METHODS AND PATIENTS

A 46,XY patient presented with mid-shaft hypospadias and cryptorchidism at birth and signs of adrenal failure at 9 yr. Mutational analysis of CYP11A1 gene was performed by PCR, followed by direct sequencing. P450scc activity was determined by measuring concentration of pregnenolone synthesized from cholesterol in the medium after a transient transfection of HEK293 cells with P450scc, adrenodoxin, adrenodoxin reductase, and steroidogenic acute regulatory protein expression plasmids.

RESULTS

The sequencing of CYP11A1 gene in the proband revealed a novel homozygous L222P mutation, whereas both parents were heterozygous carriers for this mutation. In vitro P450scc activity of L222P mutant was approximately 7% compared with the wild type.

CONCLUSIONS

This case represents the mildest phenotype of P450scc deficiency to be described. The phenotypic presentation was consistent with the partial reduction of P450scc activity of L222P mutant.