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

Primary adrenal insufficiency with normal male external genitalia in a boy with CYP11A1 deficiency

The first and rate-limiting step of steroid hormone biosynthesis is catalysed by mitochondrial cytochrome P450 side-chain cleavage enzyme (CYP11A1). CYP11A1 deficiency is commonly associated with adrenal insufficiency and, in 46 XY individuals, with variable degrees of differences in sex development (DSD). Here, we present a case report of a preadolescent male who presented to our emergency outpatient department in a state of decompensated shock necessitating ionotropic support. Further evaluation confirmed primary adrenal insufficiency. Subsequent clinical exome sequencing uncovered a compound heterozygous mutation in exons one and five of the CYP11A1 gene. This case highlights the varied presentation of CYP11A1 deficiency, showing that it can present as adrenal insufficiency without DSD.

A CYP11A1 homozygous exonic variant inducing an alternative splicing, frameshift and truncation in a family with congenital adrenal hyperplasia

Background

Congenital adrenal hyperplasia (CAH) is a heterogeneous group of adrenal steroidogenesis disorders with variable degrees of glucocorticoid, mineralocorticoid and sex steroid deficiencies. CYP11A1 gene encodes the mitochondrial cholesterol side-chain cleavage enzyme (P450scc), which initiates the first reaction in steroidogenesis by converting cholesterol to pregnenolone. Variants in this gene are extremely rare but associated with severe forms of CAH due to its early and critical function in various steroid biosynthesis pathways. Here, we report a CYP11A1 exonic homozygous variant that, although exonic in location, affects splicing by creating an additional aberrant splicing site with frameshift and truncation of the gene.

Patients and methods

The proband is a 23-year old 46,XY patient raised as a girl. She was a product of normal pregnancy for first-degree relative parents. Soon after birth, she had vomiting, dehydration, hypotension, hyponatremia and hyperkalemia. She was started on glucocorticoids and mineralocorticoids with prompt recovery. Apart from a chronic need for these medications, her neonatal and childhood history was unremarkable. She sought medical advice at age 19 years for delayed puberty with primary amenorrhea and lack of breast development. On evaluation, she had normal external female genitalia, no breast development, undescended testes and absent uterus and ovaries. Her hormonal evaluation revealed very low estrogen, testosterone, cortisol, aldosterone, 17-hydroxyprogesterone, and androstenedione levels. ACTH, LH, FSH and renin were very high consistent with primary gonadal and adrenal failure. Her parents are healthy first-degree cousins. She has three sisters, all with 46,XX karyotype. One of them is clinically and biochemically normal while the other two sisters have normal female phenotype, normal uterus and ovaries, similar hormonal profile to the proband but different karyotype (46,XX) and absence of undescended testes. gDNA was used for whole exome sequencing (WES). Sanger sequencing was performed to confirm the detected variant and its segregation with the disease.

Results

WES identified a homozygous missense variant in CYP11A1 changing the second nucleotide (GCG > GTG) at position 189 in exon 3 and resulting in a change of Alanine to Valine (p.Ala189Val). This variant was confirmed by PCR and Sanger sequencing. It was found in a homozygous form in the proband and her two affected sisters and in a heterozygous form in the unaffected sister. In-silico analysis predicted this variant to create a new splicing site with frameshift and truncation of the gene transcript. This was confirmed by isolation of RNA, cDNA synthesis, gel electrophoresis and sequencing.

Conclusion

We describe a family with a very rare form of CAH due to a CYP11A1 variant leading to creation of a new splice site, frameshift and premature truncation of the protein.

Expanding the Phenotype of Congenital Glucocorticoid Deficiency: An Iranian Patient with Cholestasis due to Pathogenic Variants in the MC2R Gene

Familial glucocorticoid deficiency is caused by variants in the MC2R and MRAP genes. We report an Iranian patient with congenital glucocorticoid deficiency and cholestasis due to pathogenic variants in the MC2R gene. This is the first documented case of a patient with conditions. Clinical evaluations and lab assessments were conducted on a six-month-old male infant. Next-generation sequencing identified the genetic causes of the disease, and Sanger sequencing confirmed the variants through segregation analysis. The clinical presentation included prolonged jaundice, progressive skin hyperpigmentation, seizures, fever, and a large umbilical hernia. Two variants in the MC2R gene, c.560delT and c.676G > C, were detected and classified as pathogenic and likely pathogenic, respectively. The cooccurrence of cholestasis and glucocorticoid deficiency illustrates the clinical heterogeneity caused by MC2R variants. The prevalence of c.560delT and c.676G > C between Iranian populations suggests these variants may be common. The high frequency of c.560delT could be attributed to a founder effect.

Aging-dependent mitochondrial bioenergetic impairment in the skeletal muscle of NNT-deficient mice

Overall health relies on features of skeletal muscle that generally decline with age, partly due to mechanisms associated with mitochondrial redox imbalance and bioenergetic dysfunction. Previously, aged mice genetically devoid of the mitochondrial NAD(P)+ transhydrogenase (NNT, encoded by the nicotinamide nucleotide transhydrogenase gene), an enzyme involved in mitochondrial NADPH supply, were shown to exhibit deficits in locomotor behavior. Here, by using young, middle-aged, and older NNT-deficient (Nnt-/-) mice and age-matched controls (Nnt+/+), we aimed to investigate how muscle bioenergetic function and motor performance are affected by NNT expression and aging. Mice were subjected to the wire-hang test to assess locomotor performance, while mitochondrial bioenergetics was evaluated in fiber bundles from the soleus, vastus lateralis and plantaris muscles. An age-related decrease in the average wire-hang score was observed in middle-aged and older Nnt-/- mice compared to age-matched controls. Although respiratory rates in the soleus, vastus lateralis and plantaris muscles did not significantly differ between the genotypes in young mice, the rates of oxygen consumption did decrease in the soleus and vastus lateralis muscles of middle-aged and older Nnt-/- mice. Notably, the soleus, which exhibited the highest NNT expression level, was the muscle most affected by aging, and NNT loss. Additionally, histology of the soleus fibers revealed increased numbers of centralized nuclei in older Nnt-/- mice, indicating abnormal morphology. In summary, our findings suggest that NNT expression deficiency causes locomotor impairments and muscle dysfunction during aging in mice.

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.

An Update on the Genetic Drivers of Corticotroph Tumorigenesis

The genetic landscape of corticotroph tumours of the pituitary gland has dramatically changed over the last 10 years. Somatic changes in the USP8 gene account for the most common genetic defect in corticotrophinomas, especially in females, while variants in TP53 or ATRX are associated with a subset of aggressive tumours. Germline defects have also been identified in patients with Cushing's disease: some are well-established (MEN1, CDKN1B, DICER1), while others are rare and could represent coincidences. In this review, we summarise the current knowledge on the genetic drivers of corticotroph tumorigenesis, their molecular consequences, and their impact on the clinical presentation and prognosis.

Late diagnosis of partial 3β-hydroxysteroid dehydrogenase type 2 deficiency - characterization of a new genetic variant

Summary

Congenital adrenal hyperplasia (CAH) is one of the most common inherited rare endocrine disorders. This case report presents two female siblings with delayed diagnosis of non-classical CAH 3β-hydroxysteroid dehydrogenase type 2 (3βHSD2D/HSD3B2) despite early hospital admission and apparent CAH manifestations such as infections, hirsutism, menstrual disturbances, and PCOS phenotype. Initially, sister 1 was misdiagnosed with PCOS and then 11-hydroxylase deficiency (CYP11B1), based on ultrasound, biochemical findings, and negative genetic testing for 21-hydroxylase deficiency (CYP21A2). Additional diagnostic workup was performed when sister 2also presented with symptoms of androgen excess. Genetic testing for CAH/steroid disorders finally revealed that both siblings were compound heterozygous for two variants in the HSD3B2 gene: a frameshift variant, c.558dup, p.(Thr187Hisfs*17) and a novel missense variant, c.65T>C, p.(Leu22Ser). A Synacthen test showed an insufficient cortisol increase. In vitro studies of the variants in a cell model revealed loss of function for the p.(Thr187Hisfs*17) and partial activity for p.(Leu22Ser) confirming non-classic CAH. Overlapping symptomatology and lack of specialized knowledge on steroid biosynthesis and associated rarest forms of CAH may explain the delayed diagnosis. However, with newer diagnostic methods comprising a less biased approach, very rare forms of non-classical CAH may no longer be overlooked in the future.

Learning points

Non-classic 3βHSD2 is likely underdiagnosed. Late diagnosis of mild non-classic 3βHSD2 does occur and one should be aware of this diagnosis. Early diagnosis of NCCAH may prevent many consequences such as severe hirsutism, prolonged menstrual irregularities, infertility, or even adrenal crisis with severe infections. Comprehensive steroid profiling and genetic testing should be used earlier, especially when in doubt about a diagnosis.

Identification of a novel homozygous NR5A1 variant in a patient with a 46,XY disorders of sex development

OBJECTIVES

Nuclear receptor subfamily 5 group A member 1 (NR5A1) is a transcription factor critical for the development of various organs. Pathogenic variants in NR5A1 are associated with a spectrum of disorders of sex development (DSD).

CASE PRESENTATION

A 15-month-old baby, raised as a girl, was referred for genital swelling and ambiguous genitalia. Born to healthy consanguineous parents, the baby had a phallus, perineal hypospadias, labial fusion, and a hypoplastic scrotum. Hormonal evaluation showed normal levels, and ultrasonography revealed small gonads and absence of Müllerian derivatives. Post-human chorionic gonadotropin (hCG) testing indicated an adequate testosterone response. The karyotype was 46,XY, and in it was found a homozygous NR5A1 variant (c.307 C>T, p.Arg103Trp) in a custom 46 XY DSD gene panel. Notably, the patient exhibited complete sex reversal, hyposplenia, and no adrenal insufficiency.

CONCLUSIONS

Previously, NR5A1 pathogenic variants were considered to be dominantly inherited, and homozygous cases were thought to be associated with adrenal insufficiency. Despite the homozygous pathogenic variant, our patient showed hyposplenism with normal adrenal function; this highlights the complexity of NR5A1 genotype-phenotype correlations. These patients should be monitored for adrenal insufficiency and DSD as well as splenic function.

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.

Single-Exon Deletions of ZNRF3 Exon 2 Cause Congenital Adrenal Hypoplasia

CONTEXT

Primary adrenal insufficiency (PAI) is a life-threatening condition characterized by the inability of the adrenal cortex to produce sufficient steroid hormones. E3 ubiquitin protein ligase zinc and ring finger 3 (ZNRF3) is a negative regulator of Wnt/β-catenin signaling. R-spondin 1 (RSPO1) enhances Wnt/β-catenin signaling via binding and removal of ZNRF3 from the cell surface.

OBJECTIVE

This work aimed to explore a novel genetic form of PAI.

METHODS

We analyzed 9 patients with childhood-onset PAI of biochemically and genetically unknown etiology using array comparative genomic hybridization. To examine the functionality of the identified single-exon deletions of ZNRF3 exon 2, we performed three-dimensional (3D) structure modeling and in vitro functional studies.

RESULTS

We identified various-sized single-exon deletions encompassing ZNRF3 exon 2 in 3 patients who showed neonatal-onset adrenal hypoplasia with glucocorticoid and mineralocorticoid deficiencies. Reverse-transcriptase polymerase chain reaction (RT-PCR) analysis showed that the 3 distinct single-exon deletions were commonly transcribed into a 126-nucleotide deleted mRNA and translated into 42-amino acid deleted protein (ΔEx2-ZNRF3). Based on 3D structure modeling, we predicted that interaction between ZNRF3 and RSPO1 would be disturbed in ΔEx2-ZNRF3, suggesting loss of RSPO1-dependent activation of Wnt/β-catenin signaling. Cell-based functional assays with the TCF-LEF reporter showed that RSPO1-dependent activation of Wnt/β-catenin signaling was attenuated in cells expressing ΔEx2-ZNRF3 as compared with those expressing wild-type ZNRF3.

CONCLUSION

We provided genetic evidence linking deletions encompassing ZNRF3 exon 2 and congenital adrenal hypoplasia, which might be related to constitutive inactivation of Wnt/β-catenin signaling by ΔEx2-ZNRF3.

Lack of NAD(P)+ transhydrogenase activity in patients with primary adrenal insufficiency due to NNT variants

BACKGROUND

Pathogenic variants in the nicotinamide nucleotide transhydrogenase gene (NNT) are a rare cause of primary adrenal insufficiency (PAI), as well as functional impairment of the gonads.

OBJECTIVE

Despite the description of different homozygous and compound heterozygous NNT variants in PAI patients, the extent to which the function and expression of the mature protein are compromised remains to be clarified.

DESIGN

The activity and expression of mitochondrial NAD(P)+ transhydrogenase (NNT) were analyzed in blood samples obtained from patients diagnosed with PAI due to genetically confirmed variants of the NNT gene (n = 5), heterozygous carriers as their parents (n = 8), and healthy controls (n = 26).

METHODS

NNT activity was assessed by a reverse reaction assay standardized for digitonin-permeabilized peripheral blood mononuclear cells (PBMCs). The enzymatic assay was validated in PBMC samples from a mouse model of NNT absence. Additionally, the PBMC samples were evaluated for NNT expression by western blotting and reverse transcription quantitative polymerase chain reaction and for mitochondrial oxygen consumption.

RESULTS

NNT activity was undetectable (<4% of that of healthy controls) in PBMC samples from patients, independent of the pathogenic genetic variant. In patients' parents, NNT activity was approximately half that of the healthy controls. Mature NNT protein expression was lower in patients than in the control groups, while mRNA levels varied widely among genotypes. Moreover, pathogenic NNT variants did not impair mitochondrial bioenergetic function in PBMCs.

CONCLUSIONS

The manifestation of PAI in NNT-mutated patients is associated with a complete lack of NNT activity. Evaluation of NNT activity can be useful to characterize disease-causing NNT variants.

A Rare Presentation of Homozygous Pathogenic Variant in MC2R Gene with Salt-Wasting Crisis in a Neonate

Introduction

Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disease resulting from isolated glucocorticoid deficiency or unresponsiveness to adrenocorticotropic hormone. Patients with FGD usually present in infancy or early childhood with hyperpigmentation, recurrent infections, and hypoglycemia. The salt-wasting crisis is rare.

Case Presentation

A term female neonate was admitted to the neonatal intensive care unit due to respiratory distress. On physical examination, she had generalized hyperpigmentation. Initial laboratory work-up yielded normal serum electrolytes and glucose. Hyponatremia and hyperkalemia emerged on follow-up. The patient was diagnosed as having primary adrenal insufficiency (PAI) with elevated plasma adrenocorticotropin hormone and reduced cortisol levels and hydrocortisone. We started on oral sodium (5 mEq/kg/day) and fludrocortisone (FC) (0.2 mg/day) treatment to the patient. Ultrasonography revealed hypoplastic adrenal glands. Molecular genetic analysis revealed a previously reported homozygous pathogenic variant NM_000529.2: c.560delT (p.V187fs*29) in the MC2R gene. FC dose was tapered to 0.05 mg/day on the third month of life and was stopped at tenth months of age with maintenance of normal serum electrolytes and clinical findings.

Conclusion

FGD due to MC2R gene mutation may rarely present with a salt-wasting crisis in the neonatal period. Identifying the causative gene with the pathogenic variant in PAI may serve to individualize a treatment plan.

A novel mutation in the NNT gene causing familial glucocorticoid deficiency, with a literature review

Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by low cortisol levels despite elevated adrenocorticotropin (ACTH). Mineralocorticoid secretion is classically normal. Clinical manifestations are secondary to low cortisol levels (recurrent hypoglycemia, chronic asthenia, failure to thrive, seizures) and high levels of ACTH (cutaneous-mucosal hyperpigmentation). FGD is often caused by mutations in the ACTH melanocortin 2 receptor gene (MC2R, 18p11.21, FGD type 1) or melanocortin receptor 2 accessory protein gene (MRAP, 21q22.11, FGD type 2). But mutations have also been described in other genes: the steroidogenic acute regulatory protein (STAR, 8q11.2q13.2, FGD type 3), nicotinamide nucleotide transhydrogenase (NNT, 5p12, FGD type 4) and thioredoxin reductase 2 genes (TXNRD2, 22q11.21, FGD type 5). We report the case of a 3-year-old boy recently diagnosed with FGD type 4 due to a novel mutation in NNT gene. A homozygous variant in exon 18 of the NNT gene, NM_012343.3:c.2764C>T, p.(Arg922*), determines a stop codon and, consequently, a non-functional truncated protein or absence of protein due to the nonsense-mediated decay (NMD) mechanism. We review the recent literature on NNT mutations and clinical presentations, which are broader than suspected. This disorder can result in significant morbidity and is potentially fatal if untreated. Precise diagnosis allows correct treatment and follow-up.

Clinical and genetic characteristics of a large international cohort of individuals with rare NR5A1/SF-1 variants of sex development

BACKGROUND

Steroidogenic factor 1 (SF-1/NR5A1) is essential for human sex development. Heterozygous NR5A1/SF-1 variants manifest with a broad range of phenotypes of differences of sex development (DSD), which remain unexplained.

METHODS

We conducted a retrospective analysis on the so far largest international cohort of individuals with NR5A1/SF-1 variants, identified through the I-DSD registry and a research network.

FINDINGS

Among 197 individuals with NR5A1/SF-1 variants, we confirmed diverse phenotypes. Over 70% of 46, XY individuals had a severe DSD phenotype, while 90% of 46, XX individuals had female-typical sex development. Close to 100 different novel and known NR5A1/SF-1 variants were identified, without specific hot spots. Additionally, likely disease-associated variants in other genes were reported in 32 individuals out of 128 tested (25%), particularly in those with severe or opposite sex DSD phenotypes. Interestingly, 48% of these variants were found in known DSD or SF-1 interacting genes, but no frequent gene-clusters were identified. Sex registration at birth varied, with <10% undergoing reassignment. Gonadectomy was performed in 30% and genital surgery in 58%. Associated organ anomalies were observed in 27% of individuals with a DSD, mainly concerning the spleen. Intrafamilial phenotypes also varied considerably.

INTERPRETATION

The observed phenotypic variability in individuals and families with NR5A1/SF-1 variants is large and remains unpredictable. It may often not be solely explained by the monogenic pathogenicity of the NR5A1/SF-1 variants but is likely influenced by additional genetic variants and as-yet-unknown factors.

FUNDING

Swiss National Science Foundation (320030-197725) and Boveri Foundation Zürich, Switzerland.

Genetic and phenotypic spectrum of non-21-hydroxylase-deficiency primary adrenal insufficiency in childhood: data from 111 Chinese patients

BACKGROUND

Primary adrenal insufficiency (PAI) is a rare but life-threatening condition. Differential diagnosis of numerous causes of PAI requires a thorough understanding of the condition.

METHODS

To describe the genetic composition and presentations of PAI. The following data were collected retrospectively from 111 patients with non-21OHD with defined genetic diagnoses: demographic information, onset age, clinical manifestations, laboratory findings and genetic results. Patients were divided into four groups based on the underlying pathogenesis: (1) impaired steroidogenesis, (2) adrenal hypoplasia, (3) resistance to adrenocorticotropic hormone (ACTH) and (4) adrenal destruction. The age of onset was compared within the groups.

RESULTS

Mutations in the following genes were identified: NR0B1 (n=39), STAR (n=33), CYP11B1 (n=12), ABCD1 (n=8), CYP17A1 (n=5), HSD3B2 (n=4), POR (n=4), MRAP (n=2), MC2R (n=1), CYP11A1 (n=1), LIPA (n=1) and SAMD9 (n=1). Frequent clinical manifestations included hyperpigmentation (73.0%), dehydration (49.5%), vomiting (37.8%) and abnormal external genitalia (23.4%). Patients with adrenal hypoplasia typically presented manifestations earlier than those with adrenal destruction but later than those with impaired steroidogenesis (both p<0.01). The elevated ACTH (92.6%) and decreased cortisol (73.5%) were the most common laboratory findings. We generated a differential diagnosis flowchart for PAI using the following clinical features: 17-hydroxyprogesterone, very-long-chain fatty acid, external genitalia, hypertension and skeletal malformation. This flowchart identified 84.8% of patients with PAI before next-generation DNA sequencing.

CONCLUSIONS

STAR and NR0B1 were the most frequently mutated genes in patients with non-21OHD PAI. Age of onset and clinical characteristics were dependent on aetiology. Combining clinical features and molecular tests facilitates accurate diagnosis.

Applications of genomic research in pediatric endocrine diseases

Recent advances in molecular genetics have advanced our understanding of the molecular mechanisms involved in pediatric endocrine disorders and now play a major role in mainstream medical practice. The spectrum of endocrine genetic disorders has 2 extremes: Mendelian and polygenic. Mendelian or monogenic diseases are caused by rare variants of a single gene, each of which exerts a strong effect on disease risk. Polygenic diseases or common traits are caused by the combined effects of multiple genetic variants in conjunction with environmental and lifestyle factors. Testing for a single gene is preferable if the disease is phenotypically and/or geneically homogeneous. Next-generation sequencing (NGS) can be applied to phenotypically and genetically heterogeneous conditions. Genome-wide association studies (GWASs) have examined genetic variants across the entire genome in a large number of individuals who have been matched for population ancestry and assessed for a disease or trait of interest. Common endocrine diseases or traits, such as type 2 diabetes mellitus, obesity, height, and pubertal timing, result from the combined effects of multiple variants in various genes that are frequently found in the general population, each of which contributes a small individual effect. Isolated founder mutations can result from a true founder effect or an extreme reduction in population size. Studies of founder mutations offer powerful advantages for efficiently localizing the genes that underlie Mendelian disorders. The Korean population has settled in the Korean peninsula for thousands of years, and several recurrent mutations have been identified as founder mutations. The application of molecular technology has increased our understanding of endocrine diseases, which have impacted on the practice of pediatric endocrinology related to diagnosis and genetic counseling. This review focuses on the application of genomic research to pediatric endocrine diseases using GWASs and NGS technology for diagnosis and treatment.

X-linked adrenoleukodystrophy and primary adrenal insufficiency

X-linked adrenoleukodystrophy (X-ALD; OMIM:300100) is a progressive neurodegenerative disorder caused by a congenital defect in the ATP-binding cassette transporters sub-family D member 1 gene (ABCD1) producing adrenoleukodystrophy protein (ALDP). According to population studies, X-ALD has an estimated birth prevalence of 1 in 17.000 subjects (considering both hemizygous males and heterozygous females), and there is no evidence that this prevalence varies among regions or ethnic groups. ALDP deficiency results in a defective peroxisomal β-oxidation of very long chain fatty acids (VLCFA). As a consequence of this metabolic abnormality, VLCFAs accumulate in nervous system (brain white matter and spinal cord), testis and adrenal cortex. All X-ALD affected patients carry a mutation on the ABCD1 gene. Nevertheless, patients with a defect on the ABCD1 gene can have a dramatic difference in the clinical presentation of the disease. In fact, X-ALD can vary from the most severe cerebral paediatric form (CerALD), to adult adrenomyeloneuropathy (AMN), Addison-only and asymptomatic forms. Primary adrenal insufficiency (PAI) is one of the main features of X-ALD, with a prevalence of 70% in ALD/AMN patients and 5% in female carriers. The pathogenesis of X-ALD related PAI is still unclear, even if a few published data suggests a defective adrenal response to ACTH, related to VLCFA accumulation with progressive disruption of adrenal cell membrane function and ACTH receptor activity. The reason why PAI develops only in a proportion of ALD/AMN patients remains incompletely understood. A growing consensus supports VLCFA assessment in all male children presenting with PAI, as early diagnosis and start of therapy may be essential for X-ALD patients. Children and adults with PAI require individualized glucocorticoid replacement therapy, while mineralocorticoid therapy is needed only in a few cases after consideration of hormonal and electrolytes status. Novel approaches, such as prolonged release glucocorticoids, offer potential benefit in optimizing hormonal replacement for X-ALD-related PAI. Although the association between PAI and X-ALD has been observed in clinical practice, the underlying mechanisms remain poorly understood. This paper aims to explore the multifaceted relationship between PAI and X-ALD, shedding light on shared pathophysiology, clinical manifestations, and potential therapeutic interventions.

Autoimmune primary adrenal insufficiency -current diagnostic approaches and future perspectives

The adrenal glands are small endocrine glands located on top of each kidney, producing hormones regulating important functions in our body like metabolism and stress. There are several underlying causes for adrenal insufficiency, where an autoimmune attack by the immune system is the most common cause. A number of genes are known to confer early onset adrenal disease in monogenic inheritance patterns, usually genetic encoding enzymes of adrenal steroidogenesis. Autoimmune primary adrenal insufficiency is usually a polygenic disease where our information recently has increased due to genome association studies. In this review, we go through the physiology of the adrenals before explaining the different reasons for adrenal insufficiency with a particular focus on autoimmune primary adrenal insufficiency. We will give a clinical overview including diagnosis and current treatment, before giving an overview of the genetic causes including monogenetic reasons for adrenal insufficiency and the polygenic background and inheritance pattern in autoimmune adrenal insufficiency. We will then look at the autoimmune mechanisms underlying autoimmune adrenal insufficiency and how autoantibodies are important for diagnosis. We end with a discussion on how to move the field forward emphasizing on the clinical workup, early identification, and potential targeted treatment of autoimmune PAI.

Epidemiology and Causes of Primary Adrenal Insufficiency in Children: A Population-Based Study

CONTEXT

Incidence and causes of primary adrenal insufficiency (PAI) have not been comprehensively studied in children.

OBJECTIVE

Our objective was to describe the epidemiology and to assess causes of PAI in Finnish children.

METHODS

A population-based descriptive study of PAI in Finnish patients aged 0-20 years.Diagnoses referring to adrenal insufficiency in children born in 1996-2016 were collected from the Finnish National Care Register for Health Care. Patients with PAI were identified by studying patient records. Incidence rates were calculated in relation to person-years in the Finnish population of same age.

RESULTS

Of the 97 patients with PAI, 36% were female. The incidence of PAI was highest during the first year of life (in females 2.7 and in males 4.0/100 000 person-years). At 1-15 years of age, the incidence of PAI in females was 0.3/100 000 and in males 0.6/100 000 person-years. Cumulative incidence was 10/100 000 persons at age of 15 years and 13/100 000 at 20 years. Congenital adrenal hyperplasia was the cause in 57% of all patients and in 88% of patients diagnosed before age of 1 year. Other causes among the 97 patients included autoimmune disease (29%), adrenoleukodystrophy (6%), and other genetic causes (6%). From the age of 5 years, most of the new cases of PAI were due to autoimmune disease.

CONCLUSION

After the first-year peak, the incidence of PAI is relatively constant through ages 1-15 years, and 1 out of 10 000 children are diagnosed with PAI before the age of 15 years.

An integrated single-cell analysis of human adrenal cortex development

The adrenal glands synthesize and release essential steroid hormones such as cortisol and aldosterone, but many aspects of human adrenal gland development are not well understood. Here, we combined single-cell and bulk RNA sequencing, spatial transcriptomics, IHC, and micro-focus computed tomography to investigate key aspects of adrenal development in the first 20 weeks of gestation. We demonstrate rapid adrenal growth and vascularization, with more cell division in the outer definitive zone (DZ). Steroidogenic pathways favored androgen synthesis in the central fetal zone, but DZ capacity to synthesize cortisol and aldosterone developed with time. Core transcriptional regulators were identified, with localized expression of HOPX (also known as Hop homeobox/homeobox-only protein) in the DZ. Potential ligand-receptor interactions between mesenchyme and adrenal cortex were seen (e.g., RSPO3/LGR4). Growth-promoting imprinted genes were enriched in the developing cortex (e.g., IGF2, PEG3). These findings reveal aspects of human adrenal development and have clinical implications for understanding primary adrenal insufficiency and related postnatal adrenal disorders, such as adrenal tumor development, steroid disorders, and neonatal stress.

Patient with adrenal insufficiency due to a de novo mutation in the NR0B1 gene

Objectives

Congenital X-linked adrenal hypoplasia is a rare disease with a known genetic basis characterized by adrenal insufficiency, hypogonadotropic hypogonadism, and a wide variety of clinical manifestations.

Case presentation

We present the case of a 26-day old male newborn with symptoms consistent with adrenal insufficiency, hyponatremia, and hyperkalemia. Following NaCl and fludrocortisone supplementation, the patient remained clinically stable. 17-OH-progesterone testing excluded congenital adrenal hyperplasia. The rest of hormones were within normal limits, except for adrenocorticotropic hormone (ACTH), which was significantly elevated, and aldosterone, which was below the reference value. Further testing included very long chain fatty acids to exclude adrenoleukodystrophy, the CYP11B2 gene (aldosterone synthase), and an MRI to screen for other morphological abnormalities. All tests yielded normal results. Finally, after cortisol deficiency was detected, expanded genetic testing revealed a mutation in the NR0B1 gene, which led to a diagnosis of congenital adrenal hypoplasia.

Conclusions

Diagnosis of congenital adrenal hypoplasia is challenging due to the heterogeneity of both clinical manifestations and laboratory abnormalities. As a result, diagnosis requires close monitoring and genetic testing.

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.

Development and function of the fetal adrenal

The adrenal cortex undergoes multiple structural and functional rearrangements to satisfy the systemic needs for steroids during fetal life, postnatal development, and adulthood. A fully functional adrenal cortex relies on the proper subdivision in regions or 'zones' with distinct but interconnected functions, which evolve from the early embryonic stages to adulthood, and rely on a fine-tuned gene network. In particular, the steroidogenic activity of the fetal adrenal is instrumental in maintaining normal fetal development and growth. Here, we review and discuss the most recent advances in our understanding of embryonic and fetal adrenal development, including the known causes for adrenal dys-/agenesis, and the steroidogenic pathways that link the fetal adrenal with the hormone system of the mother through the fetal-placental unit. Finally, we discuss what we think are the major open questions in the field, including, among others, the impact of osteocalcin, thyroid hormone, and other hormone systems on adrenal development and function, and the reliability of rodents as models of adrenal pathophysiology.

A Novel Mutation in Melanocortin Receptor 2 and a Reported Mutation in Melanocortin Receptor 2 Accessory Protein: Three Chinese Cases with Familial Glucocorticoid Deficiency

Background

Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disease characterized by glucocorticoid deficiency without mineralocorticoid deficiency. We report 3 Chinese patients with MRAP or MC2R mutations.

Case Reports

Patient 1 presented with hyperpigmentation. Endocrine investigations revealed low serum cortisol levels and elevated adrenocorticotropic hormone (ACTH) levels. Furthermore, low serum sodium was evident. She was diagnosed with FGD type 2 due to a homozygous mutation in MRAP (c.106+1delG), revealed through exome sequencing (ES). After 2-year treatment with hydrocortisone, skin hyperpigmentation was improved. Patient 2 initially presented with hyponatremia. Low cortisol levels and high levels of ACTH were subsequently detected; he was subjected to a hydrocortisone treatment during which he experienced repeated hypoglycemic attacks and pigmentation. ES revealed the same mutation as in patient 1 in MRAP (c.106+1delG), thus he was diagnosed with FGD type 2. After 6 years of age, his symptoms remarkably improved, and there was no episode of hypoglycemia. Patient 3 mainly presented with hyperpigmentation, hypoglycemic attack, and tall stature. Laboratory findings were normal except for low serum cortisol levels and high ACTH levels. She was diagnosed with FGD type 1 as ES revealed a novel homozygous mutation in MC2R (c.712C>A, p.His238Tyr). After nearly 2 years of hydrocortisone replacement therapy, the excessive growth was reduced to near normal, and the skin color returned to normal.

Conclusions

Three patients were diagnosed with FGD (one with FGD type 1 and two with FGD type 2). They all presented with hyperpigmentation and hypoglycemia; however, compared with patient 1, the clinical manifestations of patient 2 were more complicated. Patient 3 had later onset and taller stature than patients 1 and 2. A novel mutation in patient 3 expands the mutation spectrum of MC2R.

Two siblings with non-classic P450scc deficiency resulted from a novel mutation in CYP11A1 gene misdiagnosed as familial glucocorticoid deficiency

P450scc deficiency due to CYP11A1 gene mutations is a rare cause of primary adrenal insufficiency (PAI) in children. We reported two young siblings with PAI presented with hyperpigmentation. They were referred to our clinic with a diagnosis of familial glucocorticoid deficiency (FGD), another rare cause of PAI. However, further hormonal evaluation revealed increased plasma renin activity, which was not congruent with the diagnosis of FGD. Genetic analysis showed the compound heterozygous mutations in exon 8 of the CYP11A1 gene, including a missense mutation, R466W (c1396C>T), and a nonsense mutation, R439X (c1315C>T). A case responded well to hydrocortisone, while another case received prednisolone due to her unresponsiveness to hydrocortisone. To correctly diagnose P450scc deficiency, physicians should be alerted with the similarity between this disease and FGD because of their predominant glucocorticoid deficiency. Long-acting glucocorticoids may be used with caution to reach treatment goals.

Emerging phenotypes linked to variants in SAMD9 and MIRAGE syndrome

Background

Heterozygous de novo variants in SAMD9 cause MIRAGE syndrome, a complex multisystem disorder involving Myelodysplasia, Infection, Restriction of growth, Adrenal hypoplasia, Genital phenotypes, and Enteropathy. The range of additional clinical associations is expanding and includes disrupted placental development, poor post-natal growth and endocrine features. Increasingly, milder phenotypic features such as hypospadias in small for gestational age (SGA) boys and normal adrenal function are reported. Some children present with isolated myelodysplastic syndrome (MDS/monosomy 7) without MIRAGE features.

Objective

We aimed to investigate: 1) the range of reported SAMD9 variants, clinical features, and possible genotype-phenotype correlations; 2) whether SAMD9 disruption affects placental function and leads to pregnancy loss/recurrent miscarriage (RM); 3) and if pathogenic variants are associated with isolated fetal growth restriction (FGR).

Methods

Published data were analyzed, particularly reviewing position/type of variant, pregnancy, growth data, and associated endocrine features. Genetic analysis of SAMD9 was performed in products of conception (POC, n=26), RM couples, (couples n=48; individuals n=96), children with FGR (n=44), SGA (n=20), and clinical Silver-Russell Syndrome (SRS, n=8), (total n=194).

Results

To date, SAMD9 variants are reported in 116 individuals [MDS/monosomy 7, 64 (55.2%); MIRAGE, 52 (44.8%)]. Children with MIRAGE features are increasingly reported without an adrenal phenotype (11/52, 21.2%). Infants without adrenal dysfunction were heavier at birth (median 1515 g versus 1020 g; P < 0.05) and born later (median 34.5 weeks versus 31.0; P < 0.05) compared to those with adrenal insufficiency. In MIRAGE patients, hypospadias is a common feature. Additional endocrinopathies include hypothyroidism, hypo- and hyper-glycemia, short stature and panhypopituitarism. Despite this increasing range of phenotypes, genetic analysis did not reveal any likely pathogenic variants/enrichment of specific variants in SAMD9 in the pregnancy loss/growth restriction cohorts studied.

Conclusion

MIRAGE syndrome is more phenotypically diverse than originally reported and includes growth restriction and multisystem features, but without adrenal insufficiency. Endocrinopathies might be overlooked or develop gradually, and may be underreported. As clinical features including FGR, severe infections, anemia and lung problems can be non-specific and are often seen in neonatal medicine, SAMD9-associated conditions may be underdiagnosed. Reaching a specific diagnosis of MIRAGE syndrome is critical for personalized management.

The Use of Genetics for Reaching a Diagnosis in XY DSD

Reaching a firm diagnosis is vital for the long-term management of a patient with a difference or disorder of sex development (DSD). This is especially the case in XY DSD where the diagnostic yield is particularly low. Molecular genetic technology is playing an increasingly important role in the diagnostic process, and it is highly likely that it will be used more often at an earlier stage in the diagnostic process. In many cases of DSD, the clinical utility of molecular genetics is unequivocally clear, but in many other cases there is a need for careful exploration of the benefit of genetic diagnosis through long-term monitoring of these cases. Furthermore, the incorporation of molecular genetics into the diagnostic process requires a careful appreciation of the strengths and weaknesses of the evolving technology, and the interpretation of the results requires a clear understanding of the wide range of conditions that are associated with DSD.

Steroid Hormone Profiles and Molecular Diagnostic Tools in Pediatric Patients With non-CAH Primary Adrenal Insufficiency

CONTEXT

There is a significant challenge of attributing specific diagnoses to patients with primary adrenal insufficiency of unknown etiology other than congenital adrenal hyperplasia (non-CAH PAI). Specific diagnoses per se may guide personalized treatment or may illuminate pathophysiology.

OBJECTIVE

This work aimed to investigate the efficacy of steroid hormone profiles and high-throughput sequencing methods in establishing the etiology in non-CAH PAI of unknown origin.

METHODS

Pediatric patients with non-CAH PAI whose etiology could not be established by clinical and biochemical characteristics were enrolled. Genetic analysis was performed using targeted-gene panel sequencing (TPS) and whole-exome sequencing (WES). Plasma adrenal steroids were quantified by liquid chromatography-mass spectrometry and compared to that of controls. This study comprised 18 pediatric endocrinology clinics with 41 patients (17 girls, median age: 3 mo, range: 0-8 y) with non-CAH PAI of unknown etiology.

RESULTS

A genetic diagnosis was obtained in 29 (70.7%) patients by TPS. Further molecular diagnosis could not be achieved by WES. Compared to a healthy control group, patients showed lower steroid concentrations, most statistically significantly in cortisone, cortisol, and corticosterone (P < .0001, area under the receiver operating characteristic curve: .96, .88, and .87, respectively). Plasma cortisol of less than 4 ng/mL, cortisone of less than 11 ng/mL, and corticosterone of less than 0.11 ng/mL had a greater than 95% specificity to ensure the diagnosis of non-CAH PAI of unknown etiology.

CONCLUSION

Steroid hormone profiles are highly sensitive for the diagnosis of non-CAH PAI of unknown etiology, but they are unlikely to point to a specific molecular diagnosis. TPS is an optimal approach in the molecular diagnosis of these patients with high efficacy, whereas little additional benefit is expected from WES.

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.

Can Digenic, Tri-Allelic Inheritance of Variants in STAR and CYP11A1 Give Rise to Primary Adrenal Insufficiency? A Case Report

An eight-year old South Asian boy presenting with progressive hyperpigmentation was found to have primary adrenal insufficiency (PAI) in the form of isolated glucocorticoid deficiency. Follow up of this boy for nine years, until the age of 17 years showed normal pubertal onset and progression. Molecular evaluation, by targeted next generation sequencing of candidate genes linked to PAI revealed changes in two genes that are intricately linked in the early stages of steroid biosynthesis: compound heterozygous variants in STAR, c.465+1G>A and p.(E99K), plus a heterozygous rs6161 change in CYP11A1. No variants in other known causal genes were detected. The proband's mother was heterozygous for the c.465+1G>A STAR and rs6161 CYP11A1 variants, while the father was homozygous for the p.(E99K) alteration in STAR but wild-type for CYP11A1. Both parents had normal adrenal cortical function as revealed by short Synacthen tests. The STAR variant c.465+1G>A will lead to abnormal splicing of exon 4 in mRNA and the addition of the p.(E99K) variant, predicted damaging by SIFT and CADD, may be sufficient to cause PAI but this is by no means certain given that the unaffected father is homozygous for the latter change. The rs6161 CYP11A1 variant [c.940G>A, p.(E314K)] has recently been demonstrated to cause PAI in conjunction with a severe rare disruptive change on the other allele, however sequencing of the coding region of CYP11A1 revealed no further changes in this subject. We wondered whether the phenotype of isolated glucocorticoid deficiency had arisen in this child due to tri-allelic inheritance of a heterozygous CYP11A1 change along with the two STAR variants each of which contribute a partial loss-of-function burden that, when combined, is sufficient to cause PAI or if the loss-of-function c.465+1G>A combined with the presumed partial loss-of-function p.(E99K) in STAR could be causative.

Rare forms of genetic steroidogenic defects affecting the gonads and adrenals

Pathogenic variants have been found in all genes involved in the classic pathways of human adrenal and gonadal steroidogenesis. Depending on their function and severity, they cause characteristic disorders of corticosteroid and/or sex hormone deficiency, may result in atypical sex development at birth and/or puberty, and mostly lead to sexual dysfunction and infertility. Genetic disorders of steroidogenesis are all inherited in an autosomal recessive fashion. Loss of function mutations lead to typical phenotypes, while variants with partial activity may manifest with milder, non-classic, late-onset disorders that share similar phenotypes. Thus, these disorders of steroidogenesis are diagnosed by comprehensive phenotyping, steroid profiling and genetic testing using next generation sequencing techniques. Treatment comprises of steroid replacement therapies, but these are insufficient in many aspects. Therefore, studies are currently ongoing towards newer approaches such as lentiviral transmitted enzyme replacement therapy and reprogrammed stem cell-based gene therapy.

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.

A rare and preventable aetiology of neurodevelopmental delay and epilepsy: familial glucocorticoid deficiency

OBJECTIVES

Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disorder characterised by isolated glucocorticoid deficiency. Melanocortin receptor 2 (MC2R) mediates the functions of adrenocorticotropic hormone (ACTH) in the adrenal cortex. MC2R accessory protein (MRAP) is a transmembrane protein involved in the trafficking of MC2R to the cell surface. Mutations in MC2R and MRAP genes cause FGD type 1 and 2. In the present case series, we evaluate the clinical characteristics and long-term follow-up of six cases with FGD due to mutations in MC2R and MRAP.

CASE PRESENTATION

Data of six cases with FGD (five with mutations in MC2R and one with a mutation in MRAP) who were being followed at our paediatric endocrine centre was evaluated. Diagnosis of FGD was considered in case of elevated ACTH and inappropriately low cortisol level, and exclusion of other aetiologies. The main presenting complaints were hyperpigmentation and hypoglycaemic convulsion in all cases. During a follow-up period of 26-115 months, one patient with homozygous 560delT mutation in MC2R, one female with G226R mutation in MC2R and one female with IVS3ds+1delG mutation in MRAP had a neurodevelopmental delay (NDD), while the other three patients had normal neurodevelopment.

CONCLUSIONS

FGD patients due to MC2R and MRAP mutations with early diagnosis and compliance to the hydrocortisone therapy had normal neurodevelopment, while delay in diagnosis and poor compliance was associated with severe hypoglycaemic convulsions and subsequent complications NDD.

Nicotinamide nucleotide transhydrogenase mutation analysis in Chinese patients with thyroid dysgenesis

Thyroid dysgenesis (TD) accounts for 80% cases of congenital hypothyroidism, which is the most common neonatal disorder. Until now, the gene mutations have been reported associated with TD can only account for 5% cases, suggesting the genetic heterogeneity of the pathology. Nicotinamide nucleotide transhydrogenase (NNT) plays a crucial role in regulating redox homeostasis, patients carrying NNT mutations have been described with a clinical phenotype of hypothyroidism. As TD risk is increased in the context of several syndromes and redox homeostasis is vital for thyroid development and function, NNT might be a candidate gene involved in syndromic TD. Therefore, we performed target sequencing (TS) in 289 TD patients for causative mutations in NNT and conducted functional analysis of the gene mutations. TS and Sanger sequence were used to screen the novel mutations. For functional analysis, we performed western blot, measurement of NADPH/NADP_total and H₂ O₂ generation, cell proliferation, and wounding healing assay. As a result, three presumably pathogenic mutations (c.811G > A, p.Ala271Ser; c.2078G > A, p.Arg693His; and c.2581G > A, p.Val861Met) in NNT had been identified. Our results showed the damaging effect of NNT mutations on stability and catalytic activity of proteins and redox balance of cells. In conclusion, our findings provided novel insights into the role of the NNT isotype in thyroid physiopathology and broaden the spectrum of pathogenic genes associated with TD. However, the pathogenic mechanism of NNT in TD is still need to be investigated in further study.

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.

Loss of Nnt Increases Expression of Oxidative Phosphorylation Complexes in C57BL/6J Hearts

Nicotinamide nucleotide transhydrogenase (NNT) is a proton pump in the inner mitochondrial membrane that generates reducing equivalents in the form of NAPDH, which can be used for anabolic pathways or to remove reactive oxygen species (ROS). A number of studies have linked NNT dysfunction to cardiomyopathies and increased risk of atherosclerosis; however, biallelic mutations in humans commonly cause a phenotype of adrenal insufficiency, with rare occurrences of cardiac dysfunction and testicular tumours. Here, we compare the transcriptomes of the hearts, adrenals and testes from three mouse models: the C57BL/6N, which expresses NNT; the C57BL/6J, which lacks NNT; and a third mouse, expressing the wild-type NNT sequence on the C57BL/6J background. We saw enrichment of oxidative phosphorylation genes in the C57BL/B6J in the heart and adrenal, possibly indicative of an evolved response in this substrain to loss of Nnt. However, differential gene expression was mainly driven by mouse background with some changes seen in all three tissues, perhaps reflecting underlying genetic differences between the C57BL/B6J and -6N substrains.

Adrenoleukodystrophy in the Differential Diagnosis of Boys Presenting with Primary Adrenal Insufficiency without Adrenal Antibodies

Adrenoleukodystrophy (ALD) is an X-linked, metabolic disorder caused by deficiency of peroxisomal ALD protein resulting in accumulation of very-long chain fatty acids (VLCFA), primarily in the adrenal cortex and central nervous system. Approximately 35-40% of boys with ALD develop cerebral ALD (CALD), which causes rapidly progressive cerebral demyelination, loss of neurologic function, and death. Approximately 70-80% of boys with ALD have impaired adrenal function prior to the onset of neurologic symptoms. We present a boy who had recurrent episodes of hypoglycaemia from age two years and was diagnosed with adrenal insufficiency without adrenal antibodies at age 5.5 years. Following initial normal VLCFA levels, subsequent VLCFA analysis demonstrated elevated C26 fatty acids consistent with peroxisomal dysfunction and suggestive of ALD, which was confirmed via molecular genetic analysis of the ABCD1 gene. Brain imaging at age 7 suggested cerebral involvement and the child underwent successful allogeneic hematopoietic stem cell transplantation. At last assessment (11.5 years old), he was performing as expected for age. This case highlights the importance of pursuing a diagnosis when clinical suspicion remains, and the significance of VLCFA analysis for patients with adrenal insufficiency without adrenal antibodies in securing an ALD diagnosis. Subsequent brain imaging surveillance can detect early, pre-symptomatic cerebral disease, allowing for timely treatment and successful arrest of cerebral disease progression.

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.

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.

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.

Adrenal insufficiency

Adrenal insufficiency can arise from a primary adrenal disorder, secondary to adrenocorticotropic hormone deficiency, or by suppression of adrenocorticotropic hormone by exogenous glucocorticoid or opioid medications. Hallmark clinical features are unintentional weight loss, anorexia, postural hypotension, profound fatigue, muscle and abdominal pain, and hyponatraemia. Additionally, patients with primary adrenal insufficiency usually develop skin hyperpigmentation and crave salt. Diagnosis of adrenal insufficiency is usually delayed because the initial presentation is often non-specific; physician awareness must be improved to avoid adrenal crisis. Despite state-of-the-art steroid replacement therapy, reduced quality of life and work capacity, and increased mortality is reported in patients with primary or secondary adrenal insufficiency. Active and repeated patient education on managing adrenal insufficiency, including advice on how to increase medication during intercurrent illness, medical or dental procedures, and profound stress, is required to prevent adrenal crisis, which occurs in about 50% of patients with adrenal insufficiency after diagnosis. It is good practice for physicians to provide patients with a steroid card, parenteral hydrocortisone, and training for parenteral hydrocortisone administration, in case of vomiting or severe illness. New modes of glucocorticoid delivery could improve the quality of life in some patients with adrenal insufficiency, and further advances in oral and parenteral therapy will probably emerge in the next few years.

A fish with no sex: gonadal and adrenal functions partition between zebrafish NR5A1 co-orthologs

People with NR5A1 mutations experience testicular dysgenesis, ovotestes, or adrenal insufficiency, but we do not completely understand the origin of this phenotypic diversity. NR5A1 is expressed in gonadal soma precursor cells before expression of the sex-determining gene SRY. Many fish have two co-orthologs of NR5A1 that likely partitioned ancestral gene subfunctions between them. To explore ancestral roles of NR5A1, we knocked out nr5a1a and nr5a1b in zebrafish. Single-cell RNA-seq identified nr5a1a-expressing cells that co-expressed genes for steroid biosynthesis and the chemokine receptor Cxcl12a in 1-day postfertilization (dpf) embryos, as does the mammalian adrenal-gonadal (interrenal-gonadal) primordium. In 2dpf embryos, nr5a1a was expressed stronger in the interrenal-gonadal primordium than in the early hypothalamus but nr5a1b showed the reverse. Adult Leydig cells expressed both ohnologs and granulosa cells expressed nr5a1a stronger than nr5a1b. Mutants for nr5a1a lacked the interrenal, formed incompletely differentiated testes, had no Leydig cells, and grew far larger than normal fish. Mutants for nr5a1b formed a disorganized interrenal and their gonads completely disappeared. All homozygous mutant genotypes lacked secondary sex characteristics, including male breeding tubercles and female sex papillae, and had exceedingly low levels of estradiol, 11-ketotestosterone, and cortisol. RNA-seq showed that at 21dpf, some animals were developing as females and others were not, independent of nr5a1 genotype. By 35dpf, all mutant genotypes greatly under-expressed ovary-biased genes. Because adult nr5a1a mutants form gonads but lack an interrenal and conversely, adult nr5a1b mutants lack a gonad but have an interrenal, the adrenal, and gonadal functions of the ancestral nr5a1 gene partitioned between ohnologs after the teleost genome duplication, likely owing to reciprocal loss of ancestral tissue-specific regulatory elements. Identifying such elements could provide hints to otherwise unexplained cases of Differences in Sex Development.

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.

Emerging roles of melanocortin receptor accessory proteins (MRAP and MRAP2) in physiology and pathophysiology

Melanocortin-2 receptor accessory protein (MRAP) has an unusual dual topology and influences the expression, localisation, signalling and internalisation of the melanocortin receptor 2 (MC₂); the adrenocorticotropic hormone (ACTH) receptor. Mutations in MRAP are associated with familial glucocorticoid deficiency type-2 and evidence is emerging of the importance of MRAP in adrenal development and ACTH signalling. Human MRAP has two functional splice variants: MRAP-α and MRAP-β, unlike MRAP-β, MRAP-α has little expression in brain but is highly expressed in ovary. MRAP2, identified through whole human genome sequence analysis, has approximately 40% sequence homology to MRAP. MRAP2 facilitates MC2 localisation to the cell surface but not ACTH signalling. MRAP and MRAP2 have been found to regulate the surface expression and signalling of all melanocortin receptors (MC_1-5). Additionally, MRAP2 moderates the signalling of the G-protein coupled receptors (GCPRs): orexin, prokineticin and GHSR1a; the ghrelin receptor. Whilst MRAP appears to be mainly involved in glucocorticoid synthesis, an important role is emerging for MRAP2 in regulating appetite and energy homeostasis. Transgenic models indicate the importance of MRAP in adrenal gland formation. Like MC3R and MC4R knockout mice, MRAP2 knockout mice have an obese phenotype. In vitro studies indicate that MRAP2 enhances the MC3 and MC4 response to the agonist αMSH, which, like ACTH, is produced through precursor polypeptide proopiomelanocortin (POMC) cleavage. Analysis of cohorts of individuals with obesity have revealed several MRAP2 genetic variants with loss of function mutations which are causative of monogenic hyperphagic obesity with hyperglycaemia and hypertension. MRAP2 may also be associated with female infertility. This review summarises current knowledge of MRAP and MRAP2, their influence on GPCR signalling, and focusses on pathophysiology, particularly familial glucocorticoid deficiency type-2 and obesity.

The Changing Face of Adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is a rare X-linked disorder of peroxisomal oxidation due to mutations in ABCD1. It is a progressive condition with a variable clinical spectrum that includes primary adrenal insufficiency, myelopathy, and cerebral ALD. Adrenal insufficiency affects over 80% of ALD patients. Cerebral ALD affects one-third of boys under the age of 12 and progresses to total disability and death without treatment. Hematopoietic stem cell transplantation (HSCT) remains the only disease-modifying therapy if completed in the early stages of cerebral ALD, but it does not affect the course of adrenal insufficiency. It has significant associated morbidity and mortality. A recent gene therapy clinical trial for ALD reported short-term MRI and neurological outcomes comparable to historical patients treated with HSCT without the associated adverse side effects. In addition, over a dozen states have started newborn screening (NBS) for ALD, with the number of states expecting to double in 2020. Genetic testing of NBS-positive neonates has identified novel variants of unknown significance, providing further opportunity for genetic characterization but also uncertainty in the monitoring and therapy of subclinical and/or mild adrenal insufficiency or cerebral involvement. As more individuals with ALD are identified at birth, it remains uncertain if availability of matched donors, transplant (and, potentially, gene therapy) centers, and specialists may affect the timely treatment of these individuals. As these promising gene therapy trials and NBS transform the clinical management and outcomes of ALD, there will be an increasing need for the endocrine management of presymptomatic and subclinical adrenal insufficiency. (Endocrine Reviews 41: 1 - 17, 2020).

Identification of scavenger receptor BI as a potential screening candidate for congenital primary adrenal insufficiency in humans

Glucocorticoids belong to the superfamily of steroid hormones that are synthesized from the common precursor cholesterol. Adrenal gland-derived glucocorticoids, e.g., cortisol in humans and corticosterone in rodents, contribute to various processes essential for normal daily life. Glucocorticoid deficiency, also referred to as primary adrenal insufficiency, therefore, often becomes evident early in life and can be present with hypoglycemia, a failure to thrive, recurrent development of infections, and neurological problems, such as seizures and coma. The majority of congenital primary adrenal insufficiency cases are caused by deleterious mutations in genes involved in the intracellular mobilization of cholesterol and the subsequent conversion of cholesterol into glucocorticoids. A significant number of glucocorticoid deficiency cases, however, cannot be explained by known genetic variations. This perspective highlights existing literature regarding the importance of lipoprotein-derived cholesterol acquisition through scavenger receptor class B, type I (SR-BI/SCARB1) for the maintenance of an optimal adrenal glucocorticoid function in mice and humans. On the basis of the reviewed findings, it is suggested that the SCARB1 gene should be included in the standard glucocorticoid deficiency genetic screening panel to 1) facilitate knowledge development on the relative contribution of SR-BI-mediated cholesterol acquisition to steroid hormone synthesis in humans and 2) open up the possibility to reclassify glucocorticoid deficiency patients without a currently known genetic cause for concomitant treatment optimization.

Disorders of Sex Development-Novel Regulators, Impacts on Fertility, and Options for Fertility Preservation

Disorders (or differences) of sex development (DSD) are a heterogeneous group of congenital conditions with variations in chromosomal, gonadal, or anatomical sex. Impaired gonadal development is central to the pathogenesis of the majority of DSDs and therefore a clear understanding of gonadal development is essential to comprehend the impacts of these disorders on the individual, including impacts on future fertility. Gonadal development was traditionally considered to involve a primary 'male' pathway leading to testicular development as a result of expression of a small number of key testis-determining genes. However, it is increasingly recognized that there are several gene networks involved in the development of the bipotential gonad towards either a testicular or ovarian fate. This includes genes that act antagonistically to regulate gonadal development. This review will highlight some of the novel regulators of gonadal development and how the identification of these has enhanced understanding of gonadal development and the pathogenesis of DSD. We will also describe the impact of DSDs on fertility and options for fertility preservation in this context.