Analysis of DAX1 (NR0B1) and steroidogenic factor-1 (NR5A1) in children and adults with primary adrenal failure: ten years' experience

46,ΧΥ DSD in an adolescent with a novel de novo variant of the NR5A1 gene - case report and literature review

PURPOSE

In addition to chromosomal abnormalities, several genes have been implicated as causes of disorders of sex development (DSD). The NR5A1 gene expresses SF1, a transcription factor that plays a role in steroidogenesis by controlling multiple stages of adrenal and gonadal development, its mutations having been reported in cases of DSD.

CASE PRESENTATION

A 15-year-old teenager was admitted to the Children's ICU of a tertiary center due to acute encephalitis. On physical examination, labia majora and minora, open vaginal opening, and a 4.8 cm phallus (stretched length) in the anatomical position of the clitoris were identified. The patient also presented with hirsutism, breast development was Tanner stage I, and pubic hair was Tanner V. Medical history revealed primary amenorrhea. Imaging studies revealed oval formations primarily compatible with testicular parenchyma in the anatomical location of the inguinal ducts. The karyotype identified a 46,XY individual, while whole exome sequencing (WES) revealed the presence of a heterozygous pathogenic splice site variant of the NR5A1 gene (NM_004959.5), c.990G > C, p.Glu330Asp, which, on further genetic testing of the parents, was proven to be de novo. According to psychiatric assessment, the patient self-identifies as a female. Laparoscopic exploration showed no residual Mullerian ducts or the presence of testicular tissue. A gonadectomy was performed and hormone replacement therapy with estrogens was initiated.

CONCLUSION

We describe a rare case of 46,XY DSD in an phenotypically female adolescent carrying the novel de novo p.Glu330Asp variant of the NR5A1 gene. We also highlight the frequent delay in diagnosis of ambiguous external genitalia.

X-linked congenital adrenal hypoplasia: Report of long clinical follow-up and description of a new complex variant in the NR0B1 gene

Adrenal hypoplasia congenita, attributed to NR0B1 pathogenic variants, accounts for more than 50% of the incidence of primary adrenal insufficiency in children. Although more than 250 different deleterious variations have been described, no genotype-phenotype correlation has been defined to date. We report a case of an adopted boy who reported the onset of an adrenal crisis at 2 weeks of age, requiring replacement therapy with mineralocorticoids and glucocorticoids for 4 months. For 3 years, he did well without treatment. At almost 4 years of age, the disorder was restarted. A long follow-up showed the evolution of hypogonadotropic hypogonadism. Molecular studies on NR0B1 revealed a novel and deleterious deletion-insertion-inversion-deletion complex rearrangement sorted in the 5'-3' direction, which is described as follows: (1) deletion of the intergenic region (between TASL and NR0B1 genes) and 5' region, (2) insertion of a sequence containing 37 bp at the junction of the intergenic region of the TASL gene and a part of exon 1 of the NR0B1 gene, (3) inversion of a part of exon 1, (4) deletion of the final portion of exon 1 and exon 2 and beginning of the 3'UTR region, (5) maintenance of part of the intergenic sequence (between genes MAGEB1 and NR0B1, telomeric sense), (6) large posterior deletion, in the same sense. The path to molecular diagnosis was challenging and involved several molecular biology techniques. Evaluating the breakpoints in our patient, we assumed that it was a nonrecurrent rearrangement that had not yet been described. It may involve a repair mechanism known as nonhomologous end-joining (NHEJ), which joins two ends of DNA in an imprecise manner, generating an "information scar," represented herein by the 37 bp insertion. In addition, the local Xp21 chromosome architecture with sequences capable of modifying the DNA structure could impact the formation of complex rearrangements.

Role of NR5A1 Gene Mutations in Disorders of Sex Development: Molecular and Clinical Features

Disorders/differences of sex development (DSDs) are defined as broad, heterogenous groups of congenital conditions characterized by atypical development of genetic, gonadal, or phenotypic sex accompanied by abnormal development of internal and/or external genitalia. NR5A1 gene mutation is one of the principal genetic alterations implicated in causing DSD. This review outlines the role of NR5A1 gene during the process of gonadal development in humans, provides an overview of the molecular and functional characteristics of NR5A1 gene, and discusses potential clinical phenotypes and additional organ diseases due to NR5A1 mutations. NR5A1 mutations were analyzed in patients with 46,XY DSD and 46,XX DSD both during the neonatal and pubertal periods. Loss of function of the NR5A1 gene causes several different phenotypes, including some associated with disease in additional organs. Clinical phenotypes may vary, even among patients carrying the same NR5A1 variant, indicating that there is no specific genotype-phenotype correlation. Genetic tests are crucial diagnostic tools that should be used early in the diagnostic pathway, as early as the neonatal period, when gonadal dysgenesis is the main manifestation of NR5A1 mutation. NR5A1 gene mutations could be mainly associated with amenorrhea, ovarian failure, hypogonadism, and infertility during puberty. Fertility preservation techniques should be considered as early as possible.

Clinical and genetic characteristics of 42 Chinese paediatric patients with X-linked adrenal hypoplasia congenita

BACKGROUND

X-linked adrenal hypoplasia congenita (AHC) is a rare disorder characterized by primary adrenal insufficiency (PAI) and hypogonadotropic hypogonadism (HH), with limited clinical and genetic characterization.

METHODS

The clinical, biochemical, genetic, therapeutic, and follow-up data of 42 patients diagnosed with X-linked AHC were retrospectively analysed.

RESULTS

Hyperpigmentation (38/42, 90%), vomiting/diarrhoea (20/42, 48%), failure to thrive (13/42, 31%), and convulsions (7/42, 17%) were the most common symptoms of X-linked AHC at onset. Increased adrenocorticotropic hormone (ACTH) (42/42, 100%) and decreased cortisol (37/42, 88%) were the most common laboratory findings, followed by hyponatremia (32/42, 76%) and hyperkalaemia (29/42, 69%). Thirty-one patients presented with PAI within the first year of life, and 11 presented after three years of age. Three of the thirteen patients over the age of 14 exhibited spontaneous pubertal development, and ten of them experienced delayed puberty due to HH. Six patients receiving human chorionic gonadotropin (hCG) therapy exhibited a slight increase in testicular size and had rising testosterone levels (both P < 0.05). The testicular volumes of the three patients with pulsatile gonadotropin-releasing hormone (GnRH) therapy were larger than those of the six patients undergoing hCG therapy (P < 0.05), and they also exhibited some growth in terms of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone. Of the 42 patients, three had an Xp21 deletion, and 39 had an isolated DAX1 defect. Most patients (9/10) with entire DAX1 deletion accounting for 23.8% (10/42) of the total variants had early onset age of less than one year.

CONCLUSIONS

This study details the clinical features and genetic spectra of X-linked AHC. Patients with X-linked AHC show a bimodal distribution of the age of onset, with approximately 70% presenting within the first year of life. Pulsatile GnRH may be recommended for HH when hCG therapy is not satisfactory, although it is difficult to achieve normal testicular volume. The combination of clinical features and molecular tests provides information for an accurate diagnosis.

Rare forms of genetic paediatric adrenal insufficiency: Excluding congenital adrenal hyperplasia

Adrenal insufficiency (AI) is a severe endocrine disorder characterized by insufficient glucocorticoid (GC) and/or mineralocorticoid (MC) secretion by the adrenal glands, due to impaired adrenal function (primary adrenal insufficiency, PAI) or to insufficient adrenal stimulation by pituitary ACTH (secondary adrenal insufficiency, SAI) or tertiary adrenal insufficiency due to hypothalamic dysfunction. In this review, we describe rare genetic causes of PAI with isolated GC or combined GC and MC deficiencies and we also describe rare syndromes of isolated MC deficiency. In children, the most frequent cause of PAI is congenital adrenal hyperplasia (CAH), a group of adrenal disorders related to steroidogenic enzyme deficiencies, which will not be included in this review. Less frequently, several rare diseases can cause PAI, either affecting exclusively the adrenal glands or with systemic involvement. The diagnosis of these diseases is often challenging, due to the heterogeneity of their clinical presentation and to their rarity. Therefore, the current review aims to provide an overview on these rare genetic forms of paediatric PAI, offering a review of genetic and clinical features and a summary of diagnostic and therapeutic approaches, promoting awareness among practitioners, and favoring early diagnosis and optimal clinical management in suspect cases.

Growth alterations in rare forms of primary adrenal insufficiency: a neglected issue in paediatric endocrinology

Primary adrenal insufficiency (PAI) is an endocrine disorder characterized by direct adrenal failure^, with consequent glucocorticoid, and eventually mineralocorticoid, deficiency. In children, the main cause of PAI is congenital adrenal hyperplasia (CAH), due to a loss of function of adrenal steroidogenic enzymes, but also rarer forms, including autoimmune polyglandular syndrome, adrenoleucodistrophy, adrenal hypoplasia congenita, familial glucocorticoid deficiency, and Allgrove's Syndrome, may be observed. In PAI children, growth alterations represent a major issue, as both inadequate and excessive glucocorticoid replacement treatment may lead to reduced growth rate and adult height impairment. However, growth abnormalities are poorly studied in rare forms of paediatric PAI, and specific studies on growth rate in these children are currently lacking. In the present review, the currently available evidence on growth alterations in children with rare PAI forms will be summarized, with a major focus on comorbidities with a potential impact on patients' growth rate.

History of Adrenal Research: From Ancient Anatomy to Contemporary Molecular Biology

The adrenal is a small, anatomically unimposing structure that escaped scientific notice until 1564 and whose existence was doubted by many until the 18th century. Adrenal functions were inferred from the adrenal insufficiency syndrome described by Addison and from the obesity and virilization that accompanied many adrenal malignancies, but early physiologists sometimes confused the roles of the cortex and medulla. Medullary epinephrine was the first hormone to be isolated (in 1901), and numerous cortical steroids were isolated between 1930 and 1949. The treatment of arthritis, Addison's disease, and congenital adrenal hyperplasia (CAH) with cortisone in the 1950s revolutionized clinical endocrinology and steroid research. Cases of CAH had been reported in the 19th century, but a defect in 21-hydroxylation in CAH was not identified until 1957. Other forms of CAH, including deficiencies of 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase, and 17α-hydroxylase were defined hormonally in the 1960s. Cytochrome P450 enzymes were described in 1962-1964, and steroid 21-hydroxylation was the first biosynthetic activity associated with a P450. Understanding of the genetic and biochemical bases of these disorders advanced rapidly from 1984 to 2004. The cloning of genes for steroidogenic enzymes and related factors revealed many mutations causing known diseases and facilitated the discovery of new disorders. Genetics and cell biology have replaced steroid chemistry as the key disciplines for understanding and teaching steroidogenesis and its disorders.

Pleomorphism of the HPG axis with NR0B1 gene mutation - a case report of longitudinal follow-up of a proband with central precocious puberty

OBJECTIVES

X-linked adrenal hypoplasia congenita (AHC) is characterized by adrenal insufficiency and hypogonadotropic hypogonadism. Herein, we report a rare case of X-linked AHC with central precocious puberty (CPP).

CASE PRESENTATION

An 11-month-old male patient was found to have premature pubarche, enlargement of the penis, and frequent erection. LH and FSH levels after the GnRHa test were in the pubertal range. Direct sequencing revealed a heterozygous variant of the NR0B1 gene. The proband was treated with hydrocortisone and 9-alpha fludrocortisone because of the significantly elevated ACTH and renin activity. The secondary sexual characteristics relieved gradually. The serum testosterone and LH subsequently returned to the prepubertal range. The basal serum FSH values have been between 1.0 and 2.0 IU/L since the age of 2.25 years, with extremely low AMH levels beginning at 3 years.

CONCLUSIONS

The clinical course of CPP with NR0B1 variant may be temporary. HPG axis status of X-linked AHC may probably be pleomorphic during the longitudinal follow-up.

Adrenal Hypoplasia Congenita-Hypogonadotropic Hypogonadism Syndrome Due to NR0B1 Gene Mutations

Adrenal hypoplasia congenita (AHC) is a rare disorder of the adrenal gland due to mutations in the nuclear receptor superfamily 0, group B, member 1 (NR0B1) gene. It commonly presents with adrenal insufficiency and hypogonadotropic hypogonadism, but there is a wide variability in the age as well as the clinical phenotype at presentation. Also, the mechanism of pubertal abnormalities in this condition, which include not just delayed or absent pubertal development, but also precocious puberty in a small proportion of cases, is not clear. In this paper, three unrelated patients with 3 different mutations are described, who presented with variable age of onset of adrenal insufficiency, gonadal development, and puberty, highlighting the need for high index of suspicion of this condition in children presenting with atypical features of adrenal insufficiency.

An Update on Genetics of Adrenal Gland and Associated Disorders

The intricacies of human adrenal development have been under scrutiny for decades. Each year marks the identification of new genes and new interactions between gene products that ultimately will act to produce the fully functioning adult gland. Due to the complexity of this process, genetic missteps may lead to a constellation of pathologies. Recent years have identified several novel genetic causes of adrenal dysgenesis and provided new insights into previously delineated processes. SF1, DAX1 (NR0B1), CDKN1C, SAMD9, GLI3, TPIT, MC2R, MRAP, NNT, TXNRD2, AAAS, and MCM4 are among the genes which have had significant contributions to our understanding of the development and function of both adrenals and gonads. Collection and elucidation of these genetic and clinical insights are valuable tools for clinicians who diagnose and manage cases of adrenal dysfunction.

The etiology and clinical features of non-CAH primary adrenal insufficiency in children

BACKGROUND

The most common cause of primary adrenal insufficiency (PAI) in children is congenital adrenal hyperplasia; however, other genetic causes occur. There is limited epidemiological and clinical information regarding non-CAH PAI.

METHODS

Data for patients diagnosed from January 2015 to December 2021 at a tertiary hospital in northern China were retrospectively analyzed. We excluded those with CAH, which is the most common pathogenic disease among PAI patients. Next-generation sequencing was used for genetic analysis.

RESULTS

This retrospective study included 16 children (14 males and 2 females) with PAI. A genetic diagnosis was obtained for 14/16 (87.5%) individuals. Pathogenic variants occurred in 6 genes, including ABCD1 (6/16, 37.5%), NR0B1 (4/16, 25.0%), NR5A1/steroidogenic factor-1 (2/16; 12.5%), AAAS (1/16, 6.25%), and NNT (1/16, 6.25%). No genetic cause of PAI diagnosis was found in 2 girls (2/16, 12.5%).

CONCLUSIONS

Causes of PAI in children are diverse and predominantly affect males. Most PAI in children is congenital, and ABCD1 gene defects account for the largest proportion of PAI cases. Whole-exome sequencing is a tool for diagnosis. However, diagnoses are unclear in some cases.

Compendium of causative genes and their encoded proteins for common monogenic disorders

A compendium is presented of inherited monogenic disorders that have a prevalence of >1:20,000 in the human population, along with their causative genes and encoded proteins. "Simple" monogenic diseases are those for which the clinical features are caused by mutations impacting a single gene, usually in a manner that alters the sequence of the encoded protein. Of course, for a given "monogenic disorder", there is sometimes more than one potential disease gene, mutations in any one of which is sufficient to cause phenotypes of that disorder. Disease-causing mutations for monogenic disorders are usually passed on from generation to generation in a Mendelian fashion, and originate from spontaneous (de novo) germline founder mutations. In the past monogenic disorders have often been written off as targets for drug discovery because they sometimes are assumed to be rare disorders, for which the meager projected financial payoff of drug discovery and development has discouraged investment. However, not all monogenic diseases are rare. Here, we report that that currently available data identifies 72 disorders with a prevalence of at least 1 in 20,000 humans. For each, we tabulate the gene(s) for which mutations cause the spectrum of phenotypes associated with that disorder. We also identify the gene and protein that most commonly causes each disease. 34 of these disorders are caused exclusively by mutations in only a single gene and encoded protein.

Effect of Recombinant Gonadotropin on Testicular Function and Testicular Sperm Extraction in Five Cases of NR0B1 (DAX1) Pathogenic Variants

BACKGROUND

NR0B1 pathogenic variants can cause congenital adrenal hypoplasia or primary adrenal insufficiency in early childhood usually associated with hypogonadotropic hypogonadism. NR0B1 is necessary for organogenesis of the adrenal cortex and to maintain normal spermatogenesis. In humans, restoration of fertility in patients carrying NR0B1 pathogenic variants is challenging.

OBJECTIVE

The aim of the study was to investigate the clinical, hormonal, histological, spermiological, and molecular genetic characteristics of a cohort of patients with NR0B1 pathogenic variants, monitored for fertility preservation.

PATIENTS

We included five patients, including four teenagers, with NR0B1 pathogenic or likely pathogenic variants. They all had primary adrenal insufficiency and were receiving replacement therapy with glucocorticoids and mineralocorticoids. Patients received recombinant follicle-stimulating hormone and recombinant human chorionic gonadotropin in order to induce spermatogenesis. Combined gonadotropin treatment was initiated between 13 years and 15 years and 6 months for the four teenagers and at 31 years and 2 months for the only adult. Physical and hormonal assessments were performed just before starting gonadotropin treatment. After 12 months of gonadotropin treatment, physical examination and hormonal assessments were repeated, and semen analyses were performed. If no sperm cells were observed in at least 2 semen collections at 3-month interval, testicular biopsy for testicular sperm extraction was proposed.

RESULTS

Bilateral testicular volume increased from 8 ml (interquartile range, 6-9) to 12 ml (10-16) after gonadotropin treatment. Inhibin B levels were relatively stable: 110 ng/L (46-139) before and 91 ng/L (20-120) at the end of gonadotropin treatment. Azoospermia was observed in all semen analyses for all cases during gonadotropin treatment. Three patients agreed to testicular biopsy; no mature sperm cells could be retrieved in any.

CONCLUSION

We characterized a cohort of patients with NR0B1 pathogenic or likely pathogenic variants for fertility preservation by recombinant gonadotropin treatment, which began either at puberty or in adulthood. No sperm cells could be retrieved in semen samples or testicular biopsy even after gonadotropin treatment, indicating that gonadotropin treatment, even when started at puberty, is ineffective for restoring fertility.

Case report: Clinical characteristics and treatment of secondary osteoporosis induced by X-linked congenital adrenal dysplasia

OBJECTIVE

To summarize the clinical features and bone complications in a patient from a large family with X-linked congenital adrenocortical hypoplasia (AHC) and evaluate the efficacy of different treatment regimens on the prognosis of secondary osteoporosis caused by AHC at a 5-year follow-up.

METHODS

A large family with AHC was recruited, and the causative gene mutation was identified by Sanger sequencing in the proband. Clinical features as well as radiological examinations and laboratory indices of osteoporosis secondary to AHC were analyzed in this study. Meanwhile, the proband was treated with classical antiresorptive drugs (bisphosphonates) for 2 years and switched to a vitamin K₂ analogue for another 3 years, during which the efficacy of the drugs was evaluated.

RESULTS

The proband was identified as carrying a homozygous insertion mutation (p. Thr193GlyfsX13) in the NR0B1 (nuclear receptor subfamily 0, group B, member 1) gene, resulting in a premature stop codon due to a frameshift mutation. During treatment and follow-up, the proband did not respond well to bisphosphonate and developed atypical femoral fractures. Vitamin K₂ improved clinical symptoms. In terms of bone mineral density (BMD), there is no evidence of any effect of vitamin K₂ on the neck of femur, though some minor effects on spinal BMD cannot be excluded.

CONCLUSIONS

Secondary osteoporosis induced by AHC deserves clinical attention. Unlike in primary osteoporosis, the curative effect of bisphosphonates was unsatisfactory and was more likely to cause atypical femoral fractures in long-term treatment. It is suggested that bone anabolic drugs may be better alternatives.

The Genetic Backdrop of Hypogonadotropic Hypogonadism

The pituitary is an organ of dual provenance: the anterior lobe is epithelial in origin, whereas the posterior lobe derives from the neural ectoderm. The pituitary gland is a pivotal element of the axis regulating reproductive function in mammals. It collects signals from the hypothalamus, and by secreting gonadotropins (FSH and LH) it stimulates the ovary into cyclic activity resulting in a menstrual cycle and in ovulation. Pituitary organogenesis is comprised of three main stages controlled by different signaling molecules: first, the initiation of pituitary organogenesis and subsequent formation of Rathke’s pouch; second, the migration of Rathke’s pouch cells and their proliferation; and third, lineage determination and cellular differentiation. Any disruption of this sequence, e.g., gene mutation, can lead to numerous developmental disorders. Gene mutations contributing to disordered pituitary development can themselves be classified: mutations affecting transcriptional determinants of pituitary development, mutations related to gonadotropin deficiency, mutations concerning the beta subunit of FSH and LH, and mutations in the DAX-1 gene as a cause of adrenal hypoplasia and disturbed responsiveness of the pituitary to GnRH. All these mutations lead to disruption in the hypothalamic–pituitary–ovarian axis and contribute to the development of primary amenorrhea.

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.

Genetic aetiology of primary adrenal insufficiency in Chinese children

BACKGROUND

Primary adrenal insufficiency (PAI) is life-threatening, and a definitive aetiological diagnosis is essential for management and prognostication. We conducted this study to investigate the genetic aetiologies of PAI in South China and explore their clinical features.

METHODS

Seventy children were enrolled in this cross-sectional study. Clinical information was collected, and combined genetic tests were performed according to the children's manifestations. Statistical analysis was performed among the different groups. In silico or in vitro experiments were applied to determine the pathogenicity of novel variants.

RESULTS

Among the 70 children, 84.3% (59/70) were diagnosed with congenital adrenal hyperplasia (CAH), and 21-hydroxylase deficiency (21-OHD) was genetically confirmed in 91.5% of these cases. Salt wasting (SW), simple virilization (SV), and non-classic (NC) CAH accounted for 66.1% (39/59), 30.5% (18/59), and 3.4% (2/59) of the cases, respectively. The 17-hydroxyprogesterone (17-OHP) and testosterone (TES) levels were significantly higher in children with SW than with SV. The 17-OHP and cortisol levels in female SW patients were significantly higher than those in males. The 17-OHP, cortisol, dehydroepiandrosterone (DHEAS) and TES levels in female SW patients were significantly higher than those in female SV patients. Additionally, 72.7% (8/11) of uncharacterized PAI patients had positive genetic findings. Among all the patients, two novel variants in the CYP21A2 gene (c.833dupT and c.651 + 2T > G) were found. A microdeletion (Xp21.2-21.3) and five novel variants, including 2 in the NR0B1 gene (c.323-324CG > GA and c.1231_1234delCTCA), 2 in the AAAS gene (c.399 + 1G > A and c.250delT) and 1 in the NNT gene (c.2274delT), were detected. The novel variant c.399 + 1G > A in the AAAS gene was further confirmed to lead to exon 4 skipping during mRNA transcription and produce a truncated ALADIN protein.

CONCLUSIONS

We found ethnicity-based differences in the CYP21A2 gene variant spectrum among different study populations. Female 21-OHD patients tended to have higher 17-OHP and TES levels, which warrants caution in relation to the effects of virilization. Novel gene variants detected in the CYP21A2, NR0B1, AAAS and NNT genes expanded the genetic spectrum of PAI, however, further improvement of genetic testing tools beyond our protocol are still needed to uncover the complete aetiology of PAI in children.

Identification of a novel point mutation in DAX-1 gene in a patient with adrenal hypoplasia congenita

X-linked adrenal hypoplasia congenita caused by a mutation in NR0B1/DAX-1 is a rare inherited disorder. Patients with adrenal hypoplasia congenita are usually diagnosed with primary adrenal insufficiency in infancy or early childhood and present hypogonadotropic hypogonadism during adolescence. Our patient first presented with adrenal crisis at the age of 2 months, which was managed with glucocorticoids and mineralocorticoids. At the age of 17 years, testicular volumes of 5 mL each and a stretched penile length of 4 cm were noted. A combined pituitary function test showed a peak luteinizing hormone level of 2.68 mIU/mL, testosterone 13.5 ng/dL, confirming hypogonadotropic hypogonadism. After whole-exome sequencing, a new variant of DAX-1, c.881T&gt;C (p.Leu294Pro), was found. He was diagnosed with X-linked adrenal hypoplasia congenita and then treated with human choriogonadotropin for the induction of spermatogenesis as well as with steroid replacement therapy.

A novel stop-loss DAX1 variant affecting its protein-interaction with SF1 precedes the adrenal hypoplasia congenital with rare spontaneous precocious puberty and elevated hypothalamic-pituitary-gonadal/adrenal axis responses

The case study unveils the likely mechanism of a novel stop-loss DAX1 variant preceding the prolonged precocious puberty in the adrenal hypoplasia congenital (AHC) boy. A boy aged five years and nine months initially examined for the primary adrenal insufficiency symptoms. Next-generation sequencing confirmed the X-linked inheritance of a novel stop-loss DAX1 variant: c.1411T>C/p.Ter471Gln associated with AHC in the patient. The patient was subjected to a brief clinical follow-up from 11 to 15.1 years of age. The effect of the mutant-DAX1 variant (p.Ter471Gln) on DAX1-steroidogenic factor 1 (SF1) (protein-protein) interaction was studied by protein-protein docking using the ClusPro-online tool. At 5.9 yrs of age, the patient exhibited precocious puberty with the secondary sexual characteristics of Tanner 2 stage (of 9-14 yrs of age). The patient showed primary adrenal insufficiency with diminished cortisol concentrations at blood serum (25 ng/ml) and urine (3.55 μg/24 h) levels. Upon steroidal exposure, the patient showed normalized serum cortisol levels of 45-61 ng/ml. However, the precocious puberty got prolonged with the increased penis length of 8.5 cm and the bone age of 18 yrs old during the follow-up. The patient showed increased basal serum adrenocorticotropic hormone (110->2000 pg/ml) and follicle-stimulating hormone (18.4-22.3 mIU/ml) concentrations. Following an elevated hypothalamic-pituitary-gonadal axis activity witnessed upon gonarellin stimulation. Protein-protein docking confirmed a weaker interaction between the mutant-DAX1 (p.Ter471Gln) protein and the wild-SF1 protein. Overall, we hypothesize the weakened mutant-DAX1-SF1 (protein-protein) interaction could govern the prolonged precocious puberty augmented with the elevated hypothalamic-pituitary-gonadal/adrenal axis responses via SF1-induced neuronal nitric oxide synthetase activation in the patient.

Pediatric Primary Adrenal Insufficiency: A 21-year Single Center Experience

OBJECTIVE

Primary adrenal insufficiency (PAI) is a rare but potentially life-threatening condition. In childhood, PAI is usually caused by monogenic diseases. Although congenital adrenal hyperplasia (CAH) is the most common cause of childhood PAI, numerous non-CAH genetic causes have also been identified.

METHODS

Patients aged 0-18 years and diagnosed with PAI between 1998 and 2019 in a tertiary care hospital were retrospectively evaluated. After the etiologic distribution was determined, non-CAH PAI patients were evaluated in detail.

RESULTS

Seventy-three PAI patients were identified. The most common etiology was CAH (69.9%, n=51). Non-CAH etiologies accounted for 30.1% (n=22) and included adrenoleukodystrophy (ALD; n=8), familial glucocorticoid deficiency (n=3), Triple A syndrome (n=5), autoimmune adrenalitis (n=1), adrenal hypoplasia congenital (n=1), IMAGe syndrome (n=1), and other unknown etiologies (n=3). The median age at the time of AI diagnosis for non-CAH etiologies was 3.52 (0.03-15.17) years. The most frequent symptoms/clinical findings at onset were hyperpigmentation of skin (81.8%), symptoms of hypoglycemia (40.9%), and weakness/fatigue (31.8%). Hypoglycemia (50.0%), hyponatremia (36.4%) and hyperkalemia (22.7%) were prominent biochemical findings. Diagnosis of specific etiologies were proven genetically in 13 of 22 patients. A novel p.Q301* hemizygous frameshift mutation of the DAX1 gene was identified in one patient.

CONCLUSION

Etiology was determined in 86.3% of children with non-CAH PAI through specific clinical and laboratory findings with/ without molecular analysis of candidate genes. ALD was the most common etiology. Currently, advanced molecular analysis can be utilized to establish a specific genetic diagnosis for PAI in patients who have no specific diagnostic features.

Identification and Analysis of a Novel NR0B1 Mutation in Late-Onset Adrenal Hypoplasia Congenita and Hypogonadism

Objective

X-linked adrenal hypoplasia congenita (AHC) is a rare disorder characterized by primary adrenal insufficiency and hypogonadotropic hypogonadism (HHG) caused by mutations of the NR0B1/DAX1 gene. We aimed to search for the presence of any NR0B1/DAX1 gene mutations in a referred patient and to further characterize the phenotypes of the identified mutation.

Case Presentation

Herein, we report a Japanese patient with a novel missense mutation of the NR0B1/DAX1 gene resulting in adult-onset AHC and HHG. The patient was referred with diffuse skin pigmentation at 28 years of age, presented partial adrenal insufficiency and had undiagnosed incomplete HHG. Urological examination revealed severe oligospermia and testicular microlithiasis.

Results

The NR0B1/DAX1 gene mutation was identified by exome sequencing as a novel missense mutation (c.884A>T, p.Leu295His). We conducted in silico modeling of this mutant NR0B1/DAX1 protein (p.Leu295His) which affected the conserved hydrophobic core of the putative ligand-binding domain (LBD). In addition, functional analysis revealed that this mutant showed a decreased ability as a transcriptional repressor to suppress target genes, such as STAR and LHB. Furthermore, this mutant showed functionally impaired repression of steroidogenesis in human adrenocortical H295R cells.

Conclusions

We identified a novel missense mutation of the NR0B1/DAX1 gene in a patient suffering from late-onset AHC and HHG, who presented with oligospermia and testicular microlithiasis. This mutant NR0B1/DAX1 protein was found to have reduced repressor activity, according to in vitro studies, clinically consistent with the patient’s phenotypic features.

An Iranian Congenital Adrenal Hypoplasia Patient with Elevated Testosterone in Infancy due to a Novel Pathogenic Frameshift Variant in NR0B1

X-linked congenital adrenal hypoplasia due to NR0B1 mutation is characterized by hypogonadotropic hypogonadism (HH) and infertility. Here, we describe a novel pathogenic frameshift variant in NR0B1 associated with congenital adrenal hypoplasia by whole exome sequencing in an Iranian case with high level of testosterone. Clinical evaluations and pedigree drawing were performed. Point mutations, gene conversions, and large deletions of the CYP21A2 gene were checked. WES and segregation analyses were conducted. In silico analysis was also performed for the novel variant. The ACTH, 17-hydroxy progesterone c, and DHEA sulfate values were elevated up to 624.6 pg/mL, 8.6 pmol/L, and 17.8UMOL/L, respectively. No mutation was found in the CYP21A2 gene. WES identified a novel hemizygous frameshift insertion c.218_219insACCA: p.His73GlnfsTer41 variant in the NR0B1 gene with a pathogenic effect according to ACMG criteria. Genetic testing is helpful for differential diagnosis in primary adrenal insufficiency disorders. NR0B1 may be a common cause of congenital adrenal hypoplasia in our population.

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.

A non-surgical approach to 46,XY differences in sex development through hormonal suppression at puberty: a single-center case series study

PURPOSE

We aim to report outcomes and safety with hormonal suppression to facilitate gonadal preservation in a select group of patients with 46,XY differences in sex development (DSD) who are raised and identify as female yet have diagnoses with potential for androgenization at puberty.

METHODS

We performed a retrospective review of the past 10 years of DSD patients treated by a multidisciplinary program. Inclusion criteria were 46,XY DSD, female sex of rearing, risk of androgenization at puberty, and plan for hormonal suppression at puberty. Patients on hormonal suppression had at least 6 months of follow-up from initiation. We excluded those with complete gonadal dysgenesis or complete androgen insensitivity.

RESULTS

Four patients met inclusion criteria. Initial evaluation by DSD team was at a mean age of 6.6 years (3 weeks-16 years). All patients were evaluated in a coordinated multidisciplinary clinic. The diagnoses are listed in Table 1. Mean follow-up was 5.7 years (1.2-10.9 years). One patient presented as an infant, and is being monitored until Tanner stage 2 and/or serum hormonal evidence to initiate hormonal suppression. Three patients have been receiving hormonal suppression for 1.4 years (1.1-1.9 years) without side effects or complication. Three patients were initiated with estrogen replacement to promote desired breast development. At last follow-up, all patients had retained their gonads, all have female gender identity with no reported gender dysphoria, and no progression of androgenization.

CONCLUSIONS

In our initial experience, gonadal preservation with hormonal suppression is a tool in multidisciplinary management of select DSD patients with female gender identity with conditions associated with androgenization at puberty. Patients' growth, bone health, and overall psychosocial well-being will need to be monitored closely.

Development of the Pituitary Gland

The development of the anterior pituitary gland occurs in distinct sequential developmental steps, leading to the formation of a complex organ containing five different cell types secreting six different hormones. During this process, the temporal and spatial expression of a cascade of signaling molecules and transcription factors plays a crucial role in organ commitment, cell proliferation, patterning, and terminal differentiation. The morphogenesis of the gland and the emergence of distinct cell types from a common primordium are governed by complex regulatory networks involving transcription factors and signaling molecules that may be either intrinsic to the developing pituitary or extrinsic, originating from the ventral diencephalon, the oral ectoderm, and the surrounding mesenchyme. Endocrine cells of the pituitary gland are organized into structural and functional networks that contribute to the coordinated response of endocrine cells to stimuli; these cellular networks are formed during embryonic development and are maintained or may be modified in adulthood, contributing to the plasticity of the gland. Abnormalities in any of the steps of pituitary development may lead to congenital hypopituitarism that includes a spectrum of disorders from isolated to combined hormone deficiencies including syndromic disorders such as septo-optic dysplasia. Over the past decade, the acceleration of next-generation sequencing has allowed for rapid analysis of the patient genome to identify novel mutations and novel candidate genes associated with hypothalmo-pituitary development. Subsequent functional analysis using patient fibroblast cells, and the generation of stem cells derived from patient cells, is fast replacing the need for animal models while providing a more physiologically relevant characterization of novel mutations. Furthermore, CRISPR-Cas9 as the method for gene editing is replacing previous laborious and time-consuming gene editing methods that were commonly used, thus yielding knockout cell lines in a fraction of the time. © 2020 American Physiological Society. Compr Physiol 10:389-413, 2020.

Gonadotropin- and Adrenocorticotropic Hormone-Independent Precocious Puberty of Gonadal Origin in a Patient with Adrenal Hypoplasia Congenita Due to DAX1 Gene Mutation - A Case Report and Review of the Literature: Implications for the Pathomechanism

BACKGROUND/AIMS

Mutations in the DAX1 gene cause X-linked adrenal hypoplasia congenita (AHC) classically associated with hypogonadotropic hypogonadism. Unexpectedly, precocious puberty (PP) has been reported in some cases, its mechanism remaining unclear.

METHODS

We longitudinally studied a boy with AHC due to DAX1 gene mutation who developed peripheral PP at age 4.5 years. Initially he presented pubic hair, penile enlargement, advanced bone age and elevated testosterone levels. PP progressed with acne, body odour and ejaculations. In addition, we summarized reported findings of patients with DAX1 mutations and PP in the literature in a structured manner providing a basis to discuss possible pathomechanisms of PP in DAX1 patients.

RESULTS

In our patient, hydrocortisone treatment was increased to 20 mg/m2/day as suggested in similar published cases. However, despite the suppression of adrenocorticotropic hormone (ACTH), this remained without clinical effect or change in laboratory results. The progression of symptoms of pubertal development was well suppressed under cyproterone acetate treatment. Twenty-four-hour steroid urine excretion rate measurements excluded an effect of adrenal androgens and showed a prepubertal rise of excreted testosterone. Testes size remained small. GnRH testing showed peripheral PP.

CONCLUSION

We hypothesize that an intrinsic, gonadotropin- and ACTH-independent activation of steroidogenesis in the DAX1 deficient testes leads to PP in AHC patients with DAX1 mutations.

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."

Genetic Evaluation of Patients With Delayed Puberty and Congenital Hypogonadotropic Hypogonadism: Is it Worthy of Consideration?

Delayed puberty is a common reason of pediatric endocrinological consultation. It is often a self-limited (or constitutional) condition with a strong familial basis. The type of inheritance is variable but most commonly autosomal dominant. Despite this strong genetic determinant, mutations in genes implicated in the regulation of hypothalamic-pituitary-gonadal axis have rarely been identified in cases of self-limited delayed puberty and often in relatives of patients with congenital hypogonadotropic hypogonadism (i.e., FGFR1 and GNRHR genes). However, recently, next-generation sequencing analysis has led to the discovery of new genes (i.e., IGSF10, HS6ST1, FTO, and EAP1) that are implicated in determining isolated self-limited delayed puberty in some families. Despite the heterogeneity of genetic defects resulting in delayed puberty, genetic testing may become a useful diagnostic tool for the correct classification and management of patients with delayed puberty. This article will discuss the benefits and the limitations of genetic testing execution in cases of delayed puberty.

In cases of familial primary ovarian insufficiency and disorders of gonadal development, consider NR5A1/SF-1 sequence variants

RESEARCH QUESTION

Primary ovarian insufficiency (POI) is defined as the early exhaustion of ovarian function, before the age of 40 years. Its origin is genetic in 20-25% of cases. In rare cases, sequence variants of the NR5A1/SF-1 gene may result in POI, or in various disorders of gonadal development (DGD) or adrenal insufficiency.

DESIGN

This study describes the cases of two families in which the association of DGD and POI enabled a diagnosis of NR5A1 deleterious variations. Their clinical, hormonal, ultrasound and genetic characteristics are reported.

RESULTS

The mothers of the affected children were 21 and 29 years when POI was diagnosed. Each nonetheless had two spontaneous pregnancies. The children have different phenotypes and different forms of DGD. None of the affected family members had adrenal insufficiency. A new sequence variant of the NR5A1 gene was identified in one family: p.Cys283Phe (c.848G>T), and the NR5A1 sequence variant c.86G>C was found in the other family.

CONCLUSION

Sequence variation of the NR5A1 gene is a possibility that must be considered when a woman with POI or a diminished ovarian reserve has a family member or child with DGD. If a variant is identified, genetic counselling is essential for the patient and his/her family.

Breakpoint junction features of seven DMD deletion mutations

Duchenne muscular dystrophy is an inherited muscle wasting disease with severe symptoms and onset in early childhood. Duchenne muscular dystrophy is caused by loss-of-function mutations, most commonly deletions, within the DMD gene. Characterizing the junction points of large genomic deletions facilitates a more detailed model of the origins of these mutations and allows for a greater understanding of phenotypic variations associated with particular genotypes, potentially providing insights into the deletion mechanism. Here, we report sequencing of breakpoint junctions for seven patients with intragenic, whole-exon DMD deletions. Of the seven junction sequences identified, we found one instance of a “clean” break, three instances of microhomology (2–5 bp) at the junction site, and three complex rearrangements involving local sequences. Bioinformatics analysis of the upstream and downstream breakpoint regions revealed a possible role of short inverted repeats in the initiation of some of these deletion events.

Researchers in Australia have identified new examples of the genomic factors and mechanisms that lead to deletions linked with Duchenne muscular dystrophy (DMD). DMD is an inherited neuromuscular disease which causes progressive deterioration of muscles and, in some cases, intellectual impairment. Using samples from seven DMD patients, Niall Keegan of Murdoch University in Perth and colleagues sequenced the DNA left behind around the deletions in the DMD gene which cause the disease. They found one clean break, three sections with short repeated sequences, and three with more complex rearrangements. The diversity of these findings led them to suggest that the deletions resulted from a diversity of genomic factors and repair mechanisms. Future work could incorporate these findings into a model to predict where deletions will occur, expanding our understanding of DMD and its causes.

Novel mutations and spectrum of the disease of NR0B1 (DAX1)-related adrenal insufficiency in Indian children

Background X-linked adrenal hypoplasia congenita (AHC), due to mutations in the nuclear receptor superfamily 0, group B, member 1 (NR0B1)/dosage-sensitive sex reversal, AHC, critical region on the X chromosome, gene 1 (DAX1) gene, usually presents with a salt-wasting adrenal crisis in infancy and hypogonadotropic hypogonadism (HH) in adolescents. Genetic reports in the literature from patients of diverse ethnicity are limited. We describe the atypical clinical characteristics and molecular genetic results in six Indian patients. Methods Both exons and flanking intronic sequences of the NR0B1 gene were amplified and sequenced in five patients. In the sixth patient, suspected to have a large deletion, multiplex ligation-dependent probe amplification (MLPA) and chromosomal microarray analysis were performed. Results Sequencing revealed three novel mutations: a nonsense mutation (c.776C > A), a deletion (c.298del), both causing loss of domains which are highly conserved among nuclear receptor families, and a missense mutation (c.1112T > C). In-silico analysis by structure-based protein modeling predicted a de-stabilizing effect of the novel missense mutation. Two previously reported mutations were seen in patients with atypical manifestations such as late-onset adrenal insufficiency and precocious puberty. One patient had a 7.15-Mb contiguous deletion involving the NR0B1, Duchenne muscular dystrophy (DMD), glycerol kinase (GK) and melanoma antigen, family B, 16 (MAGEB16) genes. Conclusions Our report emphasizes the wide clinical spectrum of AHC, including rare manifestations, and enumerates unique mutations in the NR0B1 gene.

Androgen receptor signalling in the male adrenal facilitates X-zone regression, cell turnover and protects against adrenal degeneration during ageing

Androgens are known to be an essential regulator of male health. Androgen receptor (AR) is widely expressed throughout the adrenal cortex, yet the wider role for androgen signalling in the adrenal remains underexplored. To investigate AR-dependent and AR-independent androgen signalling in the adrenal, we used a novel mouse model with a specific ablation of androgen receptor in the adrenal cortex with or without reduction of circulating androgen levels by castration. Our results describe AR expression in the human and mouse adrenal and highlight that the mouse is a viable model to investigate androgen signalling in the adrenal cortex. We show androgen signalling via AR is required for X-zone regression during puberty. Furthermore, cortex measurements define differences in X-zone morphology depending on whether circulating androgens or AR have been removed. We show androgens promote both cortical cell differentiation and apoptosis but are dispensable for the formation of the definitive cortex. Additionally, investigation of aged mice with AR ablation reveals severe cortex disruption, spindle cell hyperplasia and X-zone expansion. The data described herein demonstrates AR-signalling is required to facilitate X-zone regression, cell clearance and to protect against adrenal degeneration during ageing.

Isolated hypoaldosteronism as first sign of X-linked adrenal hypoplasia congenita caused by a novel mutation in NR0B1/DAX-1 gene: a case report

Background

X-linked Adrenal Hypoplasia Congenita (AHC) is a rare cause of primary adrenal insufficiency due to mutations in the NR0B1 gene, causing a loss of function of the nuclear receptor protein DAX-1. Adrenal insufficiency usually appears in the first 2 months of life, but can sometimes emerge during childhood. Hypogonadotropic Hypogonadism is often associated later in life and patients may develop azoospermia. We describe an unusual onset of AHC started with isolated hypoaldosteronism as first and only sign of the disease.

Case presentation

A 18-days-old newborn presented with failure to thrive and feeding difficulties. Blood tests showed severe hyponatremia, hyperkalemia and hypochloremia. Renin was found over the measurable range and aldosterone was low whereas cortisol level was normal with a slightly increased ACTH. In the suspicion of Primary Hypoaldosteronism, correction of plasmatic electrolytes and replacement therapy with Fludrocortisone were promptly started. The subsequent evidence of low plasmatic and urinary cortisol and increased ACTH required the start of Hydrocortisone replacement therapy and it defined a clinical picture of adrenal insufficiency. Genetic analysis demonstrated a novel mutation in the DAX-1 gene leading to the diagnosis of AHC.

Conclusions

AHC onset may involve the aldosterone production itself, miming an isolated defect of aldosterone synthesis. NR0B1/DAX-1 mutations should be considered in male infants presenting with isolated hypoaldosteronism as first sign of adrenal insufficiency.

Hyponatremic Seizures and Adrenal Hypoplasia Congenita in a Neonate with Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) in neonates may occur as an isolated finding, in association with other anomalies, or as part of a genetic syndrome. We report the first case of an infant with CDH who presented with hyponatremic seizures due to adrenal hypoplasia congenita (AHC). The patient underwent repair of CDH defect. After an uncomplicated postoperative course while on discharge planning, he developed a seizure episode associated with severe hyponatremia and hyperkalemia. Extensive diagnostic workup revealed an NR0B1 gene variant confirming the diagnosis of X-linked AHC. The patient was eventually discharged home on hydrocortisone, fludrocortisone, and salt supplements. There are a few case reports of adrenal insufficiency in neonates with CDH, manifesting with symptoms before and immediately after reparative surgery. Clinical presentation of our patient was unique in manifesting as neonatal seizure secondary to severe hyponatremia after a stable postoperative phase. The patient's electrolytes and hemodynamic status remained stable before, during, and after surgery for CDH. This case underlines the importance of taking detailed family history and continued vigilance for signs and symptoms of adrenal insufficiency in infants with repaired CDH by pediatricians and intensivists.

Identification and Functional Analysis of Six DAX1 Mutations in Patients With X-Linked Adrenal Hypoplasia Congenita

Context

DAX1 (NR0B1) mutations cause X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH) in affected male patients. Affected individuals typically present with early-onset adrenal insufficiency and develop HH during puberty. Rare cases can present with late-onset adrenal insufficiency or other unusual phenotypes.

Objectives

We sought to identify and functionally characterize DAX1 mutations in seven Thai male subjects in six families with X-linked AHC.

Patients and Methods

Six patients had classic phenotypes with early-onset adrenal failure. One patient presented with late-onset Addison disease at 17 years. In the early-onset group, one patient had GnRH-independent sexual precocity at 3 years of age, and another patient had growth hormone deficiency. The DAX1 gene was sequenced from all patients, and the transcriptional activities of the identified mutations were assessed in vitro using luciferase assays.

Results

DAX1 mutations were identified in all patients, including three novel mutations [c.363delG (p.Gly122Valfs*142), c.1062delC (p.Ala355Profs*17), and c.1156C>T (p.Leu386Phe)] and three known mutations [c.1148_1149delGG (p.Gly383Aspfs*5), c.501_502insG (p.Ala170Argfs*15), and c.805_807delGTC (p.Val269del)]. Functional studies showed that the DAX1 mutants had lower levels of repressor activity on the StAR gene promoter compared with the wild-type DAX-1 protein.

Conclusions

This study describes unusual phenotypes and three novel mutations, extending the phenotypic and mutational spectra of DAX1 mutations.

Novel NR5A1 mutations found in Chinese patients with 46, XY disorders of sex development

OBJECTIVE

To analyze nuclear receptor subfamily 5 group A member 1 (NR5A1) gene mutations in a cohort of Chinese patients with 46, XY Disorders of Sex Development (DSD).

METHODS

Sixty 46, XY DSD patients were recruited at Peking Union Medical College Hospital. Targeted next-generation and Sanger sequencing were performed to investigate pathogenic gene variants and validate NR5A1 gene variants, respectively. In silico tools and in vitro function studies were used to analyze the pathogenicity of rare variants. The clinical and endocrinological characteristics of patients with NR5A1 variants were retrospectively analyzed.

RESULTS

A total of four novel and three recurrent NR5A1 variants were identified in seven 46, XY DSD patients. These variants widely spread almost all the functional domains. Functional studies showed that novel mutations including p.S32N, p.N44del and p.G91D reduced transactivation of CYP11A1, while the other missense variant p.A168E did not impact protein function. All patients with NR5A1 rare variants had normal adrenal function and showed genital defects. Results of the genitalia examination showed female external genitalia (three patients), ambiguous external genitalia (two patients), female external genitalia with clitoromegaly (one patient), and hypospadias (one patient). All seven patients had bilateral testis and five of seven patients lacked Müllerian structures.

CONCLUSIONS

Four novel mutations in the NR5A1 gene were identified in our cohort with 46, XY DSD, expanding the spectrum of NR5A1 gene mutations. All patients with NR5A1 rare variants had normal adrenal function and showed genital defects.

Sex chromosomes-linked single-gene disorders involved in human infertility

Human infertility is a healthcare problem that has a worldwide impact. Genetic causes of human infertility include chromosomal aneuploidies and rearrangements and single-gene defects. The sex chromosomes (X and Y) are critical players in human fertility since they contain several genes essential for sex determination and reproductive traits for both men and women. This paper provides a review of the most common sex chromosomes-linked single-gene disorders involved in human infertility and their corresponding phenotypes. In addition to the Y-linked SRY gene, which mutations may cause XY gonadal dysgenesis and sex reversal, the deletions of genes present in AZF regions of the Y chromosome (DAZ, RBMY, DBY and USP9Y genes) are implicated in varying degrees of spermatogenic dysfunction. Furthermore, a list of X-linked genes (KAL1, NR0B1, AR, TEX11, FMR1, PGRMC1, BMP15 and POF1 and 2 regions genes (XPNPEP2, POF1B, DACH2, CHM and DIAPH2)) were reported to have critical roles in pubertal and reproductive deficiencies in humans, affecting only men, only women or both sexes. Mutations in these genes may be transmitted to the offspring by a dominant or a recessive inheritance.

At the Crossroads of Fate-Somatic Cell Lineage Specification in the Fetal Gonad

The reproductive endocrine systems are vastly different between males and females. This sexual dimorphism of the endocrine milieu originates from sex-specific differentiation of the somatic cells in the gonads during fetal life. Most gonadal somatic cells arise from the adrenogonadal primordium. After separation of the adrenal and gonadal primordia, the gonadal somatic cells initiate sex-specific differentiation during gonadal sex determination with the specification of the supporting cell lineages: Sertoli cells in the testis vs granulosa cells in the ovary. The supporting cell lineages then facilitate the differentiation of the steroidogenic cell lineages, Leydig cells in the testis and theca cells in the ovary. Proper differentiation of these cell types defines the somatic cell environment that is essential for germ cell development, hormone production, and establishment of the reproductive tracts. Impairment of lineage specification and function of gonadal somatic cells can lead to disorders of sexual development (DSDs) in humans. Human DSDs and processes for gonadal development have been successfully modeled using genetically modified mouse models. In this review, we focus on the fate decision processes from the initial stage of formation of the adrenogonadal primordium in the embryo to the maintenance of the somatic cell identities in the gonads when they become fully differentiated in adulthood.

Testicular microlithiasis in a boy with X-linked adrenal hypoplasia congenita

X-linked adrenal hypoplasia congenita (AHC) is a rare disorder that usually presents clinically as adrenal insufficiency in early infancy. It is caused by mutations in the NR0B1 gene which is located on the short arm of chromosome X (Xp21). The NR0B1 gene plays an important role in normal development and function of both the adrenal and gonadal axes and some patients with the disease can present in adolescence with hypogonadotropic hypogonadism. Testicular microlithiasis is an ultrasonographic finding of unknown etiology that has been associated with several benign conditions such as cryptorchidism, congenital adrenal hyperplasia, varicoceles, and testicular malignancy. We report the case of an 11-year-old boy who was diagnosed at the age of 8 months with X-linked AHC due to adrenal failure and presented testicular microlithiasis during follow-up. To the best of our knowledge, this is the first case of an X-linked AHC patient diagnosed with testicular microlithiasis in follow-up.

A novel de novo frameshift mutation in NR0B1 and low prenatal estriol in adrenal hypoplasia congenita

Mutations in the gene NR0B1 have been associated with several clinical phenotypes of X-linked adrenal hypoplasia congenita (AHC). The degree and onset of adrenal insufficiency and involvement of hypogonadotropic hypogonadism is variable and may not be concordant with the identified mutation. We review a patient with AHC in which prenatal estriol levels were low, presenting with early-onset mineralocorticoid deficiency in the newborn period followed by glucocorticoid deficiency 2 years later. The reported child is hemizygous for a novel mutation that is deemed de novo in the ligand-binding site of the protein (DAX1) expressed by NR0B1. The identified frameshift mutation results in a T407N/fs protein change. Low prenatal estriol levels may represent a sensitive marker of potentially fatal disorders associated with adrenal insufficiency and should be utilized more frequently. Additionally, accurate reporting of mutations in NR0B1 and the associated phenotype are important to eventually establish a genotype-phenotype correlation that may help anticipate guidance in AHC.

Primary adrenal insufficiency in children: Diagnosis and management

Primary adrenal insufficiency (PAI) is a life-threatening disorder of adrenal cortex which is characterized by deficient biosynthesis of glucocorticoids, with or without deficiency in mineralocorticoids and adrenal androgens. Typical manifestations of primary adrenal insufficiency include hyperpigmentation, hypotension, hypoglycaemia, hyponatremia with or without hyperkalemia that are generally preceded by nonspecific symptoms at the onset. Recessively inherited monogenic disorders constitute the largest group of primary adrenal insufficiency in children. The diagnostic process of primary adrenal insufficiency includes demonstration of low cortisol concentrations along with high plasma ACTH and identifying the cause of the disorder. Specific molecular diagnosis is achieved in more than 80% of children with PAI by detailed clinical and biochemical characterization integrated with advanced molecular tools. Hormone replacement therapy determined on the type and the severity of deficient adrenocortical hormones is the mainstay of treatment. Optimized methods of steroid hormone delivery, improved monitoring of hormone replacement along with intensive education of patients and families on the rules during intercurrent illness and stress will significantly reduce the morbidity and mortality associated with primary adrenal insufficiency.

GENETICS IN ENDOCRINOLOGY: Genetic counseling for congenital hypogonadotropic hypogonadism and Kallmann syndrome: new challenges in the era of oligogenism and next-generation sequencing

Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS) are rare, related diseases that prevent normal pubertal development and cause infertility in affected men and women. However, the infertility carries a good prognosis as increasing numbers of patients with CHH/KS are now able to have children through medically assisted procreation. These are genetic diseases that can be transmitted to patients' offspring. Importantly, patients and their families should be informed of this risk and given genetic counseling. CHH and KS are phenotypically and genetically heterogeneous diseases in which the risk of transmission largely depends on the gene(s) responsible(s). Inheritance may be classically Mendelian yet more complex; oligogenic modes of transmission have also been described. The prevalence of oligogenicity has risen dramatically since the advent of massively parallel next-generation sequencing (NGS) in which tens, hundreds or thousands of genes are sequenced at the same time. NGS is medically and economically more efficient and more rapid than traditional Sanger sequencing and is increasingly being used in medical practice. Thus, it seems plausible that oligogenic forms of CHH/KS will be increasingly identified making genetic counseling even more complex. In this context, the main challenge will be to differentiate true oligogenism from situations when several rare variants that do not have a clear phenotypic effect are identified by chance. This review aims to summarize the genetics of CHH/KS and to discuss the challenges of oligogenic transmission and also its role in incomplete penetrance and variable expressivity in a perspective of genetic counseling.

Latest Insights on the Etiology and Management of Primary Adrenal Insufficiency in Children

Primary adrenal insufficiency (PAI) is a heterogeneous group of disorders characterized by an impaired production of cortisol and other steroid hormones by the adrenal cortex. Most of the causes of PAI in childhood are inherited and monogenic in origin and are associated with significant morbidity and mortality whenever the diagnosis and treatment is delayed. Therefore, early and accurate diagnosis would allow appropriate management for the patients and genetic counselling for the family. Congenital adrenal hyperplasia accounts for most cases of PAI in childhood, followed by abnormalities in the development of the adrenal gland, resistance to adrenocorticotropin hormone action and adrenal destruction. In recent years, the use of genome-wide, next-generation sequencing approaches opened new avenues for identifying novel genetic causes in the PAI spectrum. Understanding the genetic basis of adrenal disorders is key to develop innovative therapies for patients with PAI. The promising progress made in congenital adrenal hyperplasia treatment brings new perspectives for personalized treatment in children with PAI. The aim of this review is to characterize recent advances in the genetics and management of PAI in children.

A novel DAX-1 (NR0B1) mutation in a boy with X-linked adrenal hypoplasia congenita

BACKGROUND

X-linked adrenal hypoplasia congenita (AHC) is caused by mutations in DAX-1 (NR0B1) playing a key role in adrenal and reproductive development.

CASE PRESENTATION

Herein we report a 2.5-year-old boy who presented with acute adrenal failure. Family history revealed unexplained death in three brothers of the patient's mother during infancy. Molecular analysis of the DAX-1 gene revealed the presence of a novel hemizygous mutation, c.870C>A in exon 1, leading to the formation of a premature stop codon. The same mutation was identified in the patient's mother. The truncated mutant protein is most likely misfolded, sequestered in the endoplasmic reticulum and therefore cannot bind to and activate its target DNA sequences in the nucleus.

CONCLUSIONS

DAX-1 mutation must be considered when diagnosis of primary adrenocortical insufficiency is made, especially if there is a history of unexplained death of maternal male relatives.