A Single-Center, Observational Study of 607 Children and Young People Presenting With Differences of Sex Development (DSD).

Context: Differences of sex development (DSD) represent a wide range of conditions presenting at different ages to various health professionals. Establishing a diagnosis, supporting the family, and developing a management plan are important. Objective: We aimed to better understand the presentation and prevalence of pediatric DSD. Methods: A retrospective, observational cohort study was undertaken in a single tertiary pediatric center of all children and young people (CYP) referred to a DSD multidisciplinary team over 25 years (1995-2019). In total, 607 CYP (520 regional referrals) were included. Data were analyzed for diagnosis, sex-assignment, age and mode of presentation, additional phenotypic features, mortality, and approximate point prevalence. Results: Among the 3 major DSD categories, sex chromosome DSD was diagnosed in 11.2% (68/607) (most commonly 45,X/46,XY mosaicism), 46,XY DSD in 61.1% (371/607) (multiple diagnoses often with associated features), while 46,XX DSD occurred in 27.7% (168/607) (often 21-hydroxylase deficiency). Most children (80.1%) presented as neonates, usually with atypical genitalia, adrenal insufficiency, undescended testes or hernias. Those presenting later had diverse features. Rarely, the diagnosis was made antenatally (3.8%, n = 23) or following incidental karyotyping/family history (n = 14). Mortality was surprisingly high in 46,XY children, usually due to complex associated features (46,XY girls, 8.3%; 46,XY boys, 2.7%). The approximate point prevalence of neonatal referrals for investigation of DSD was 1 in 6347 births, and 1 in 5101 overall throughout childhood. Conclusion: DSD represent a diverse range of conditions that can present at different ages. Pathways for expert diagnosis and management are important to optimize care.

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 DESIGN SETTING AND PARTICIPANTS: Unpublished and published data were reviewed for 155 young people in the United Kingdom who underwent genetic analysis for PAI of unknown etiology in three major research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.

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

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

Thioredoxin Reductase 2 (TXNRD2) mutation associated with familial glucocorticoid deficiency (FGD).

CONTEXT: Classic ACTH resistance, due to disruption of ACTH signaling, accounts for the majority of cases of familial glucocorticoid deficiency (FGD). Recently FGD cases caused by mutations in the mitochondrial antioxidant, nicotinamide nucleotide transhydrogenase, have highlighted the importance of redox regulation in steroidogenesis. OBJECTIVE: We hypothesized that other components of mitochondrial antioxidant systems would be good candidates in the etiology of FGD. DESIGN: Whole-exome sequencing was performed on three related patients, and segregation of putative causal variants confirmed by Sanger sequencing of all family members. A TXNRD2-knockdown H295R cell line was created to investigate redox homeostasis. SETTING: The study was conducted on patients from three pediatric centers in the United Kingdom. PATIENTS: Seven individuals from a consanguineous Kashmiri kindred, six of whom presented with FGD between 0.1 and 10.8 years, participated in the study. INTERVENTIONS: There were no interventions. MAIN OUTCOME MEASURE: Identification and functional interrogation of a novel homozygous mutation segregating with the disease trait were measured. RESULTS: A stop gain mutation, p.Y447X in TXNRD2, encoding the mitochondrial selenoprotein thioredoxin reductase 2 (TXNRD2) was identified and segregated with disease in this extended kindred. RT-PCR and Western blotting revealed complete absence of TXNRD2 in patients homozygous for the mutation. TXNRD2 deficiency leads to impaired redox homeostasis in a human adrenocortical cell line. CONCLUSION: In contrast to the Txnrd2-knockout mouse model, in which embryonic lethality as a consequence of hematopoietic and cardiac defects is described, absence of TXNRD2 in humans leads to glucocorticoid deficiency. This is the first report of a homozygous mutation in any component of the thioredoxin antioxidant system leading to inherited disease in humans.

Familial glucocorticoid deficiency: a diagnostic challenge during acute illness.

UNLABELLED: Familial glucocorticoid deficiency (FGD) is a heterogeneous condition of isolated glucocorticoid deficiency due to adrenocorticotropic hormone (ACTH) resistance. Patients have adrenal failure with normal electrolytes. We report two Arab children with different forms of FGD, in whom the diagnosis was initially masked by their acute illness and discuss the reasons for the delay in the diagnosis of FGD in both patients. Patient 1 presented at 12 days with Serratia sepsis. She received hydrocortisone for septic shock and needed dexamethasone courses to wean her off ventilation. At 13 weeks, she had normal electrolytes, low cortisol and high ACTH in keeping with FGD. A homozygous missense mutation (T159) in MC2R confirmed the diagnosis of FGD type 1. Patient 2 was admitted at 4.5 years, with an acute exacerbation of chronic asthma. At presentation, he had hypotension, hypoglycaemia and normal electrolytes. He was given IV hydrocortisone to treat his severe asthma, and his lip hyperpigmentation was thought to be central cyanosis. Two weeks later, his lips remained dark, and cortisol was low, with markedly elevated ACTH. Family history revealed a sister aged 22 years with cerebral palsy and a healthy 15-year-old brother, who were both severely pigmented with high ACTH levels. The diagnosis of FGD type 2 was confirmed by identifying a homozygous missense mutation (p.Y59D) in MRAP in the three siblings. CONCLUSIONS: FGD can be easily overlooked during acute illness. In a sick child, paired measurement of serum cortisol with ACTH prior to starting steroid therapy would be useful in making the diagnosis of FGD.

Familial glucocorticoid deficiency: New genes and mechanisms.

Familial Glucocorticoid deficiency (FGD), in which the adrenal cortex fails to produce glucocorticoids, was first shown to be caused by defects in the receptor for ACTH (MC2R) or its accessory protein (MRAP). Certain mutations in the steroidogenic acute regulatory protein (STAR) can also masquerade as FGD. Recently mutations in mini chromosome maintenance-deficient 4 homologue (MCM4) and nicotinamide nucleotide transhydrogenase (NNT), genes involved in DNA replication and antioxidant defence respectively, have been recognised in FGD cohorts. These latest findings expand the spectrum of pathogenetic mechanisms causing adrenal disease and imply that the adrenal may be hypersensitive to replicative and oxidative stresses. Over time patients with MCM4 or NNT mutations may develop other organ pathologies related to their impaired gene functions and will therefore need careful monitoring.

Mutations in NNT encoding nicotinamide nucleotide transhydrogenase cause familial glucocorticoid deficiency.

Using targeted exome sequencing, we identified mutations in NNT, an antioxidant defense gene, in individuals with familial glucocorticoid deficiency. In mice with Nnt loss, higher levels of adrenocortical cell apoptosis and impaired glucocorticoid production were observed. NNT knockdown in a human adrenocortical cell line resulted in impaired redox potential and increased reactive oxygen species (ROS) levels. Our results suggest that NNT may have a role in ROS detoxification in human adrenal glands.

MCM4 mutation causes adrenal failure, short stature, and natural killer cell deficiency in humans.

An interesting variant of familial glucocorticoid deficiency (FGD), an autosomal recessive form of adrenal failure, exists in a genetically isolated Irish population. In addition to hypocortisolemia, affected children show signs of growth failure, increased chromosomal breakage, and NK cell deficiency. Targeted exome sequencing in 8 patients identified a variant (c.71-1insG) in minichromosome maintenance-deficient 4 (MCM4) that was predicted to result in a severely truncated protein (p.Pro24ArgfsX4). Western blotting of patient samples revealed that the major 96-kDa isoform present in unaffected human controls was absent, while the presence of the minor 85-kDa isoform was preserved. Interestingly, histological studies with Mcm4-depleted mice showed grossly abnormal adrenal morphology that was characterized by non-steroidogenic GATA4- and Gli1-positive cells within the steroidogenic cortex, which reduced the number of steroidogenic cells in the zona fasciculata of the adrenal cortex. Since MCM4 is one part of a MCM2-7 complex recently confirmed as the replicative helicase essential for normal DNA replication and genome stability in all eukaryotes, it is possible that our patients may have an increased risk of neoplastic change. In summary, we have identified what we believe to be the first human mutation in MCM4 and have shown that it is associated with adrenal insufficiency, short stature, and NK cell deficiency.