NR0B1 (DAX1) mutations in patients affected by congenital adrenal hypoplasia with growth hormone deficiency as a new finding

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.

Nonsense variant of NR0B1 causes hormone disorders associated with congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a rare X-linked recessive inherited disease that is considered a major cause of steroidogenesis disorder and is associated with variants or complete deletion of the NR0B1 gene. The DAX-1 protein (encoded by NR0B1) is a vertebrate-specific orphan nuclear receptor and is also a transcriptional factor for adrenal and reproductive development. CAH usually causes adrenal insufficiency in infancy and early childhood, leading to hypogonadotropic hypogonadism in adulthood; however, few adult cases have been reported to date. In this study, we examined a Chinese family with one adult patient with CAH, and identified a putative variant of NR0B1 gene via next-generation sequencing (NGS), which was confirmed with Sanger sequencing. A novel nonsense variant (c.265C>T) was identified in the NR0B1 gene, which caused the premature termination of DAX-1 at residue 89 (p.G89*). Furthermore, mutant NR0B1 gene displayed a partial DAX-1 function, which may explain the late pathogenesis in our case. Additionally, qPCR revealed the abnormal expression of four important genes identified from ChIP-seq, which were associated with energy homeostasis and steroidogenesis, and were influenced by the DAX-1 mutant. In addition, hormone disorders can be caused by DAX-1 mutant and partially recovered by siRNA of PPARGC1A. Herein, we identified a novel nonsense variant (c.265C>T) of NR0B1 in a 24-year-old Chinese male who was suffering from CAH. This mutant DAX-1 protein was found to have disordered energy homeostasis and steroidogenesis based on in vitro studies, which was clinically consistent with the patient’s phenotypic features.

Defects in GnRH Neuron Migration/Development and Hypothalamic-Pituitary Signaling Impact Clinical Variability of Kallmann Syndrome

Kallmann syndrome (KS) is a combination of isolated hypogonadotropic hypogonadism (IHH) with olfactory dysfunction, representing a heterogeneous disorder with a broad phenotypic spectrum. The genetic background of KS has not yet been fully established. This study was conducted on 46 Polish KS subjects (41 males, 5 females; average age: 29 years old). The studied KS patients were screened for defects in a 38-gene panel with next-generation sequencing (NGS) technology. The analysis revealed 27 pathogenic and likely pathogenic (P/LP) variants, and 21 variants of uncertain significance (VUS). The P/LP variants were detected in 20 patients (43.5%). The prevalence of oligogenic P/LP defects in selected genes among KS patients was 26% (12/46), whereas the co-occurrence of other variants was detected in 43% (20 probands). The examined KS patients showed substantial genotypic and phenotypic variability. A marked difference in non-reproductive phenotypes, involving defects in genes responsible for GnRH neuron development/migration and genes contributing to pituitary development and signaling, was observed. A comprehensive gene panel for IHH testing enabled the detection of clinically relevant variants in the majority of KS patients, which makes targeted NGS an effective molecular tool. The significance of oligogenicity and the high incidence of alterations in selected genes should be further elucidated.

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 Novel NR0B1 Gene Mutation Causes Different Phenotypes in Two Male Patients with Congenital Adrenal Hypoplasia

X-linked congenital adrenal hypoplasia is characterised by the acute onset of primary adrenal insufficiency in infancy or early childhood and hypogonadotropic hypogonadism (HH) at puberty, arising from mutations of the nuclear receptor subfamily 0 group B member 1 (NR0B1) gene. This study investigated an extended family with two affected males (patient A: 23 years and patient B: 2 months old) and three carrier females. Sequencing analysis of the NR0B1 gene coding region from the family revealed a novel hemizygous deletion [c.604delT; p.(C202Afs*62)] in the two male patients. Furthermore, the patients' respective mothers and their common grandmother had this heterozygous mutation, but it was not present in the Human Gene Mutation Database. The two male patients showed inconsistent clinical features at onset, particularly in early childhood; however, it is possible that the younger patient will eventually show a delay of puberty, feminisation, and nonspermatogenesis in adulthood, similar to that in the older patient. Identification of a novel NR0B1 mutation in this family is important for the diagnosis and genetic counselling of children with primary adrenal insufficiency and HH, and will be helpful for predicting long-term clinical symptoms.

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.

Novel frameshift mutation of the NR0B1(DAX1) in two tall adult brothers

NR0B1 (nuclear receptor subfamily 0, group B, member 1) is a transcription factor encoded by DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1) responsible for the development and maintenance of the steroidogenic tissues. In humans the DAX1 mutations cause congenital adrenal hypoplasia (AHC) and hypogonadotropic hypogonadism (HHG) in boys. Here we report two brothers who were assessed by endocrinologist at the age of 51 and 43 because of their serious osteoporosis. They had been substituted with prednisolone since the age of 4 and 9 years because of their primary adrenal insufficiency (PAI). Due to their late puberty caused by HHG at the age of 16 and 17 years their heights were - 3.1 and - 3.3 SD, but then they had a significant growth during their adulthood and reached the + 1.85 SD and + 3.78 SD respectively. During this period, they received glucocorticoid supplementation, but the treatment of their HHG was inadequate. At the age of 51 and 43 years insulin tolerance test (ITT) and gonadotropin releasing hormone (GnRH) test confirmed their PAI and HHG. Genetic test performed at this time revealed a novel, four nucleotides deletion (del.586-571c.GGGC or 572-575c.GGGC) of DAX1 gene. The two brothers with AHC and HHG caused by a novel DAX1 mutation, reached tall final heights, despite of the disadvantageous prednisolone treatment during their childhood. We assume that the long-term lack of the sexual hormone substitution was a significant reason of their above average height as well as their serious osteoporosis.

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.

Identification of a novel mutation of NR0B1 in a patient with X-linked adrenal hypoplasia and symptomatic treatment

BACKGROUND

X-linked congenital adrenal hypoplasia (X-linked AHC) is characterized by acute onset of primary adrenal insufficiency in infancy or early childhood and hypogonadotropic hypogonadism (HH) at puberty. Mutations in NR0B1, the gene located on Xp21.3 and encoding an orphan nuclear receptor named DAX1, are responsible for this disease.

METHODS

The entire coding region of the NR0B1 gene of a 14-year-old X-linked AHC proband as well as his family members was sequenced. Clinical and endocrine evaluations with symptomatic treatment results were recorded.

RESULTS

DNA sequencing revealed a missense mutation (c.383-384 insA) in exon 1, which resulted in a novel frameshift mutation, thereby resulting in a truncated protein (p.Leu129 Pro fs*137). The therapeutic trail with an observation period of 20 weeks showed an effective improvement in symptoms of hypogonadism with human chorionic gonadotropin (HCG) administration, including a rapid improvement of serum testosterone level, descending of testicles as well as enlargement of testicles and growth of penis.

CONCLUSIONS

Our study identified a novel frameshift mutation of the NR0B1 gene in a proband with X-linked AHC/HH and further expanded the number of NR0B1 mutations reported in the literature. Moreover, the symptomatic treatment observation provided referential evidence in the treatment of X-linked AHC associated hypogonadism and bilateral inguinal cryptorchidism.

X-Linked Adrenal Hypoplasia Congenita in a Boy due to a Novel Deletion of the Entire NR0B1 (DAX1) and MAGEB1-4 Genes

X-linked Adrenal Hypoplasia Congenita (AHC) is caused by deletions or point mutations in the NR0B1 (DAX1) gene. We present a boy with AHC who came at the age of 25 days in a severe state due to prolonged vomiting and progressive dehydration. Laboratory studies showed prominent hyponatremia and hyperkaliemia but not hypoglycemia. Primary adrenal insufficiency was confirmed with low serum cortisol levels and high plasma ACTH levels. Hydrocortisone therapy combined with saline and glucose infusions was started immediately after blood collection. Two exons of the NR0B1 (DAX1) gene were impossible to amplify using the standard PCR method. Array CGH was used to confirm the putative copy-number variation of NR0B1 (DAX1) revealing a novel hemizygous deletion encompassing the entire NR0B1 (DAX1) gene together with the MAGEB genes. This genetic defect was also present in heterozygosity in the patient's mother. We show that NR0B1 (DAX1) gene analysis is important for confirmation of AHC diagnosis and highlights the role of genetic counseling in families with AHC patients, particularly those with X chromosome microdeletions, covering more than NR0B1 (DAX1) alone. We hope that further clinical follow-up of this patient and his family will shed a new light on the role of MAGEB genes.

Genetic regulation of mammalian gonad development

Sex-specific gonadal development starts with formation of the bipotential gonad, which then differentiates into either a mature testis or an ovary. This process is dependent on activation of either the testis-specific or the ovary-specific pathway while the opposite pathway is continuously repressed. A network of transcription factors tightly regulates initiation and maintenance of these distinct pathways; disruption of these networks can lead to disorders of sex development in humans and male-to-female or female-to-male sex reversal in mice. Sry is the Y-linked master switch that is both required and sufficient to drive the testis-determining pathway. Another key component of the testis pathway is Sox9, which acts immediately downstream of Sry. In contrast to the testis pathway, no single sex-determining factor has been identified in the ovary pathway; however, multiple genes, such as Foxl2, Rspo1, Ctnnb1, and Wnt4, seem to work synergistically and in parallel to ensure proper ovary development. Our understanding of the regulatory networks that underpin testis and ovary development has grown substantially over the past two decades.