Low-dose diazoxide is safe and effective in infants with transient hyperinsulinism.

OBJECTIVE: Transient hyperinsulinism (THI) is the most common form of recurrent hypoglycaemia in neonates beyond the first week of life. Although self-resolving, treatment can be required. Consensus guidelines recommend the lower end of the diazoxide 5-15 mg/kg/day range in THI to reduce the risk of adverse events. We sought to determine if doses <5 mg/kg/day of diazoxide can be effective in THI. DESIGN, PATIENTS, MEASURMENTS: Infants with THI (duration <6 months) were treated with low-dose diazoxide from October 2015 to February 2021. Dosing was based on weight at diazoxide start: 2 mg/kg/day in infants 1000-2000 g (cohort 1), 3 mg/kg/day in those 2000-3500 g (cohort 2) and 5 mg/kg/day in those >3500 g. RESULTS: A total of 73 infants with THI (77% male, 33% preterm, 52% small-for-gestational age) were commenced on diazoxide at a median age of 11 days (range 3-43) for a median duration of 4 months (0.3-6.8), with no difference between cohorts. The mean effective diazoxide dose was 3 mg/kg/day (range 1.5-10); 35% (26/73) required an increase from their starting dose, including 60% (9/15) of cohort 1. There was no association between perinatal stress risk factors or treatment-related characteristics and dose increase. Adverse events occurred in 13 patients (18%); oedema (12%) and hyponatraemia (5%) were the most common. Two infants developed suspected necrotising enterocolitis (NEC); none had pulmonary hypertension. CONCLUSION: Diazoxide doses <5 mg/kg/day are effective in THI. While the nature of the association between diazoxide and NEC was unclear, other adverse events were mild. We suggest considering starting doses as low as 2-3 mg/kg/day in THI to balance the side effect risk while maintaining euglycaemia.

Tolvaptan and urea in paediatric hyponatraemia.

BACKGROUND: The syndrome of inappropriate antidiuretic hormone (SIADH) is usually treated with fluid restriction. This can be challenging in patients with obligate fluid intake for nutrition or medication. Pharmaceutical treatment with tolvaptan and urea is available but minimal paediatric data are available. We review the efficacy and safety of tolvaptan and urea in paediatric patients with SIADH. METHODS: Retrospective review of paediatric inpatients with clinical diagnosis of SIADH. Patients were identified from pharmacy records based on tolvaptan and urea prescriptions. Relevant information was extracted from patient electronic records. The main outcome measures included the number of days to sodium normalisation, the daily change in plasma sodium concentration, and the maximum increase of plasma sodium concentration in 24 h. Reported side effects were captured. RESULTS: Thirteen patients received tolvaptan and six urea. Five patients had both agents (tolvaptan converted to urea). Tolvaptan led to plasma sodium normalisation in 10/13 (77%) within 6 days (median 2.5 days, range [1, 6]), with a median change of sodium concentration of 7 mmol/L (- 1, 14) within the first 24 h of treatment. Three patients experienced a change in plasma sodium > 10 mmol/l/day but had no apparent side effects. Urea led to sodium normalisation in 5/6 (83%) patients. The median number of days to normalisation with urea was 2 (1, 10) with a median change of plasma sodium concentration of 2 mmol/L (- 1, 6) within the first 24 h. All patients tolerated tolvaptan and/or urea without unexpected side effects. CONCLUSIONS: Tolvaptan and urea appear to be safe and effective when fluid restriction is challenging in paediatric SIADH. A higher resolution version of the Graphical abstract is available as Supplementary information.

Identification of genetic variants and phenotypic characterization of a large cohort of patients with congenital hypopituitarism and related disorders.

PURPOSE: Congenital hypopituitarism (CH) disorders are phenotypically variable. Variants in multiple genes are associated with these disorders, with variable penetrance and inheritance. METHODS: We screened a large cohort (N = 1765) of patients with or at risk of CH using Sanger sequencing, selected according to phenotype, and conducted next-generation sequencing (NGS) in 51 families within our cohort. We report the clinical, hormonal, and neuroradiological phenotypes of patients with variants in known genes associated with CH. RESULTS: We identified variants in 178 patients: GH1/GHRHR (51 patients of 414 screened), PROP1 (17 of 253), POU1F1 (15 of 139), SOX2 (13 of 59), GLI2 (7 of 106), LHX3/LHX4 (8 of 110), HESX1 (8 of 724), SOX3 (9 of 354), OTX2 (5 of 59), SHH (2 of 64), and TCF7L1, KAL1, FGFR1, and FGF8 (2 of 585, respectively). NGS identified 26 novel variants in 35 patients (from 24 families). Magnetic resonance imaging showed prevalent hypothalamo-pituitary abnormalities, present in all patients with PROP1, GLI2, SOX3, HESX1, OTX2, LHX3, and LHX4 variants. Normal hypothalamo-pituitary anatomy was reported in 24 of 121, predominantly those with GH1, GHRHR, POU1F1, and SOX2 variants. CONCLUSION: We identified variants in 10% (178 of 1765) of our CH cohort. NGS has revolutionized variant identification, and careful phenotypic patient characterization has improved our understanding of CH. We have constructed a flow chart to guide genetic analysis in these patients, which will evolve upon novel gene discoveries.

Pathogenic variants in RNPC3 are associated with hypopituitarism and primary ovarian insufficiency.

PURPOSE: We aimed to investigate the molecular basis underlying a novel phenotype including hypopituitarism associated with primary ovarian insufficiency. METHODS: We used next-generation sequencing to identify variants in all pedigrees. Expression of Rnpc3/RNPC3 was analyzed by in situ hybridization on murine/human embryonic sections. CRISPR/Cas9 was used to generate mice carrying the p.Leu483Phe pathogenic variant in the conserved murine Rnpc3 RRM2 domain. RESULTS: We described 15 patients from 9 pedigrees with biallelic pathogenic variants in RNPC3, encoding a specific protein component of the minor spliceosome, which is associated with a hypopituitary phenotype, including severe growth hormone (GH) deficiency, hypoprolactinemia, variable thyrotropin (also known as thyroid-stimulating hormone) deficiency, and anterior pituitary hypoplasia. Primary ovarian insufficiency was diagnosed in 8 of 9 affected females, whereas males had normal gonadal function. In addition, 2 affected males displayed normal growth when off GH treatment despite severe biochemical GH deficiency. In both mouse and human embryos, Rnpc3/RNPC3 was expressed in the developing forebrain, including the hypothalamus and Rathke's pouch. Female Rnpc3 mutant mice displayed a reduction in pituitary GH content but with no reproductive impairment in young mice. Male mice exhibited no obvious phenotype. CONCLUSION: Our findings suggest novel insights into the role of RNPC3 in female-specific gonadal function and emphasize a critical role for the minor spliceosome in pituitary and ovarian development and function.

A homozygous Y443C variant in the RNPC3 is associated with severe syndromic congenital hypopituitarism and diffuse brain atrophy.

Biallelic RNPC3 variants have been reported in a few patients with growth hormone deficiency, either in isolation or in association with central hypothyroidism, congenital cataract, neuropathy, developmental delay/intellectual disability, hypogonadism, and pituitary hypoplasia. To describe a new patient with syndromic congenital hypopituitarism and diffuse brain atrophy due to RNPC3 mutations and to compare her clinical and molecular characteristics and pituitary functions with previously published patients. A 20-year-old female presented with severe growth, neuromotor, and developmental delay. Her weight, height, and head circumference were 5135 gr (-25.81 SDS), 68 cm (-16.17 SDS), and 34 cm (-17.03 SDS), respectively. She was prepubertal, and had dysmorphic facies, contractures, and spasticity in the extremities, and severe truncal hypotonia. There were no radiological signs of a skeletal dysplasia. The bone age was extremely delayed at 2 years. Investigation of pituitary function revealed growth hormone, prolactin, and thyroid-stimulating hormone deficiencies. Whole-exome sequencing revealed a novel homozygous missense (c.1328A > G; Y443C) variant in RNPC3. Cranial MRI revealed a hypoplastic anterior pituitary with diffuse cerebral and cerebellar atrophy. The Y443C variant in RNPC3 associated with syndromic congenital hypopituitarism and abnormal brain development. This report extends the RNPC3-related hypopituitarism phenotype with a severe neurodegenerative presentation.

Mutations in thyroid hormone receptor α1 cause premature neurogenesis and progenitor cell depletion in human cortical development.

Mutations in the thyroid hormone receptor α 1 gene (THRA) have recently been identified as a cause of intellectual deficit in humans. Patients present with structural abnormalities including microencephaly, reduced cerebellar volume and decreased axonal density. Here, we show that directed differentiation of THRA mutant patient-derived induced pluripotent stem cells to forebrain neural progenitors is markedly reduced, but mutant progenitor cells can generate deep and upper cortical layer neurons and form functional neuronal networks. Quantitative lineage tracing shows that THRA mutation-containing progenitor cells exit the cell cycle prematurely, resulting in reduced clonal output. Using a micropatterned chip assay, we find that spatial self-organization of mutation-containing progenitor cells in vitro is impaired, consistent with down-regulated expression of cell-cell adhesion genes. These results reveal that thyroid hormone receptor α1 is required for normal neural progenitor cell proliferation in human cerebral cortical development. They also exemplify quantitative approaches for studying neurodevelopmental disorders using patient-derived cells in vitro.

Mutations in TOP3A Cause a Bloom Syndrome-like Disorder.

Bloom syndrome, caused by biallelic mutations in BLM, is characterized by prenatal-onset growth deficiency, short stature, an erythematous photosensitive malar rash, and increased cancer predisposition. Diagnostically, a hallmark feature is the presence of increased sister chromatid exchanges (SCEs) on cytogenetic testing. Here, we describe biallelic mutations in TOP3A in ten individuals with prenatal-onset growth restriction and microcephaly. TOP3A encodes topoisomerase III alpha (TopIIIα), which binds to BLM as part of the BTRR complex, and promotes dissolution of double Holliday junctions arising during homologous recombination. We also identify a homozygous truncating variant in RMI1, which encodes another component of the BTRR complex, in two individuals with microcephalic dwarfism. The TOP3A mutations substantially reduce cellular levels of TopIIIα, and consequently subjects' cells demonstrate elevated rates of SCE. Unresolved DNA recombination and/or replication intermediates persist into mitosis, leading to chromosome segregation defects and genome instability that most likely explain the growth restriction seen in these subjects and in Bloom syndrome. Clinical features of mitochondrial dysfunction are evident in several individuals with biallelic TOP3A mutations, consistent with the recently reported additional function of TopIIIα in mitochondrial DNA decatenation. In summary, our findings establish TOP3A mutations as an additional cause of prenatal-onset short stature with increased cytogenetic SCEs and implicate the decatenation activity of the BTRR complex in their pathogenesis.

Congenital growth hormone deficiency associated with hip dysplasia and Legg-Calve-Perthes disease.

OBJECTIVE: Growth hormone deficiency (GHD) is usually treated with recombinant human GH (rhGH), and this has been rarely associated with hip disorders. We analysed the clinical data of patients with congenital GHD receiving rhGH who had associated hip dysplasia or Legg-Calve-Perthes disease (LCPD), with a view to determining whether the hip dysplasia was associated with the underlying disease or with rhGH treatment. DESIGN: We performed a retrospective analysis of paediatric and adolescent patients seen between 1992-2018 with congenital GHD and hip disorders. Data were collected through a review of the patients' medical records and included demographics, clinical and imaging data, and the time frame between the onset of the symptoms related to the hip disorders and the onset of GH treatment. RESULTS: Of the 13 patients with hip disorders, hip dysplasia was present in ten patients and LCPD in three. Hip dysplasia was diagnosed before rhGH was initiated in 50% of cases. These patients had bilateral hip dysplasia and isolated GHD. LCPD was diagnosed in one patient before rhGH was commenced and did not progress. In two patients, LCPD was diagnosed after rhGH was started and did temporarily progress in one of them, but rhGH was not discontinued because LCPD did not seem to be related to rhGH treatment. CONCLUSIONS: This study suggests that hip dysplasia could be a manifestation of an underlying GHD. Additionally, rhGH treatment may not necessarily be causative of LCPD.

Syndromic Forms of Hyperinsulinaemic Hypoglycaemia-A 15-year follow-up Study.

OBJECTIVE: Hyperinsulinaemic hypoglycaemia (HH) is one of the commonest causes of hypoglycaemia in children. The molecular basis includes defects in pathways that regulate insulin release. Syndromic conditions like Beckwith-Wiedemann (BWS), Kabuki (KS) and Turner (TS) are known to be associated with a higher risk for HH. This systematic review of children with HH referred to a tertiary centre aims at estimating the frequency of a syndromic/multisystem condition to help address stratification of genetic analysis in infants with HH. METHODS: We performed a retrospective study of 69 patients with syndromic features and hypoglycaemia in a specialist centre from 2004 to 2018. RESULTS: Biochemical investigations confirmed HH in all the cases and several genetic diagnoses were established. Responsiveness to medications and the final outcome following medical treatment or surgery were studied. CONCLUSIONS: This study highlights the association of HH with a wide spectrum of syndromic diagnoses and that children with features suggestive of HH-associated syndromes should be monitored for hypoglycaemia. If hypoglycaemia is documented, they should also be screened for possible HH. Our data indicate that most syndromic forms of HH are diazoxide-responsive and that HH resolves over time; however, a significant percentage continues to require medications years after the onset of the disease. Early diagnosis of hyperinsulinism and initiation of treatment is important for preventing hypoglycaemic brain injury and intellectual disability.

Clinical benefits of sex steroids given as a priming prior to GH provocative test or as a growth-promoting therapy in peripubertal growth delays: Results of a retrospective study among ENDO-ERN centres.

OBJECTIVES: Sex steroids, administered as a priming before GH stimulation tests (GHST) to differentiate between growth hormone deficiency (GHD) and constitutional delay of growth and puberty (CDGP) or as growth-promoting therapy using low-dose sex steroids (LDSS) in CDGP, are much debated. We aimed to compare auxological outcomes of CDGP or GHD children undergoing primed or unprimed GHST and to evaluate LDSS treatment in CDGP. DESIGN: Retrospective study among three paediatric University Hospitals in Italy and UK. METHODS: 184 children (72 females) aged 12.4 ± 2.08 years underwent primed (/P+ ) or unprimed (/P- ) GHST and were followed up until final height (FH). CDGP patients were untreated (CDG P- ) or received LDSS (CDGP+ ). The cohort included 34 CDG P- /P+ , 12 CDGP+ /P+ , 51 GHD/P+ , 29 CDG P- /P- , 2 CDGP+ /P- and 56 GHD/P- . FH standard deviation score (SDS), Δ SDS FH-target height (TH) and degree of success (-1 ≤ Δ SDS FH-SDS TH ≤ +1) were outcomes of interest. RESULTS: GHD/P+ had better FH-SDS (-0.87 vs -1.49; P = .023) and ΔSDS FH-TH (-0.35 vs -0.77; P = .002) than CDGP- /P+ . Overall, GHD/P+ showed the highest degree of success (90%, P = .006). Regardless of priming, both rhGH and LDSS improved degree of success compared to no treatment (89% and 86% vs 63%, P = .0009). GHD/P+ showed a trend towards a higher proportion of permanent GHD compared to GHD/P- (30.43% vs 15.09%; P = .067). CONCLUSION: In peripubertal children, priming before GHST improves diagnostic accuracy of GHST for idiopathic GHD. LDSS treatment improves auxological outcomes in CDGP.

Hyperinsulinemic hypoglycemia in children and adolescents: Recent advances in understanding of pathophysiology and management.

Hyperinsulinemic hypoglycemia (HH) is characterized by unregulated insulin release, leading to persistently low blood glucose concentrations with lack of alternative fuels, which increases the risk of neurological damage in these patients. It is the most common cause of persistent and recurrent hypoglycemia in the neonatal period. HH may be primary, Congenital HH (CHH), when it is associated with variants in a number of genes implicated in pancreatic development and function. Alterations in fifteen genes have been recognized to date, being some of the most recently identified mutations in genes HK1, PGM1, PMM2, CACNA1D, FOXA2 and EIF2S3. Alternatively, HH can be secondary when associated with syndromes, intra-uterine growth restriction, maternal diabetes, birth asphyxia, following gastrointestinal surgery, amongst other causes. CHH can be histologically characterized into three groups: diffuse, focal or atypical. Diffuse and focal forms can be determined by scanning using fluorine-18 dihydroxyphenylalanine-positron emission tomography. Newer and improved isotopes are currently in development to provide increased diagnostic accuracy in identifying lesions and performing successful surgical resection with the ultimate aim of curing the condition. Rapid diagnostics and innovative methods of management, including a wider range of treatment options, have resulted in a reduction in co-morbidities associated with HH with improved quality of life and long-term outcomes. Potential future developments in the management of this condition as well as pathways to transition of the care of these highly vulnerable children into adulthood will also be discussed.

Transcription factor 7-like 1 is involved in hypothalamo-pituitary axis development in mice and humans.

Aberrant embryonic development of the hypothalamus and/or pituitary gland in humans results in congenital hypopituitarism (CH). Transcription factor 7-like 1 (TCF7L1), an important regulator of the WNT/ß-catenin signaling pathway, is expressed in the developing forebrain and pituitary gland, but its role during hypothalamo-pituitary (HP) axis formation or involvement in human CH remains elusive. Using a conditional genetic approach in the mouse, we first demonstrate that TCF7L1 is required in the prospective hypothalamus to maintain normal expression of the hypothalamic signals involved in the induction and subsequent expansion of Rathke's pouch progenitors. Next, we reveal that the function of TCF7L1 during HP axis development depends exclusively on the repressing activity of TCF7L1 and does not require its interaction with ß-catenin. Finally, we report the identification of two independent missense variants in human TCF7L1, p.R92P and p.R400Q, in a cohort of patients with forebrain and/or pituitary defects. We demonstrate that these variants exhibit reduced repressing activity in vitro and in vivo relative to wild-type TCF7L1. Together, our data provide support for a conserved molecular function of TCF7L1 as a transcriptional repressor during HP axis development in mammals and identify variants in this transcription factor that are likely to contribute to the etiology of CH.

Pathogenesis of Growth Failure in Rasopathies.

The RASopathies are a group of developmental genetic syndromes that are caused by germline mutations in genes encoding proteins of the Ras-Mitogen-Activated Protein kinase (RAS-MAPK) pathway. RASopathies include Noonan Syndrome (NS), Neurofibromatosis Type 1 (NF1), Noonan syndrome with multiple lentigines (NSML/LEOPARD), Costello syndrome (CS), Cardio-facio-cutaneous syndrome (CFC), capillary malformation-arteriovenous malformation syndrome (CM-AVM) and Legius Syndrome. These syndromes have many overlapping features; however, the most persistent feature common to all is the postnatal growth failure. The mechanism of growth failure in Rasopathies is highly complex and there are many proposed hypotheses including partial growth hormone insensitivity, growth hormone deficiency, neurosecretory dysfunction of growth hormone secretion, delayed puberty, poor feeding and skeletal abnormalities. Amongst these causes, the most widely accepted is partial growth hormone insensitivity due to a post-receptor signaling defect. Growth hormone therapy seems to be effective in improving height velocity in these syndromes, although the long-term effects on final height remain unproven. However, it is important to consider the potential risk of tumors and cardiomyopathy before and during growth hormone therapy.

A novel IGSF1 mutation in a large Irish kindred highlights the need for familial screening in the IGSF1 deficiency syndrome.

OBJECTIVE: Loss-of-function mutations in IGSF1 result in X-linked central congenital hypothyroidism (CeCH), occurring in isolation or associated with additional pituitary hormone deficits. Intrafamilial penetrance is highly variable and a minority of heterozygous females are also affected. We identified and characterized a novel IGSF1 mutation and investigated its associated phenotypes in a large Irish kindred. DESIGN, PATIENTS AND MEASUREMENTS: A novel hemizygous IGSF1 mutation was identified by direct sequencing in two brothers with CeCH, and its functional consequences were characterized in vitro. Genotype-phenotype correlations were investigated in the wider kindred. RESULTS: The mutant IGSF1 protein (c.2318T > C, p.L773P) exhibited decreased plasma membrane expression in vitro due to impaired trafficking from the endoplasmic reticulum. Ten hemizygous males and 11 heterozygous females exhibited characteristic endocrine deficits. Ireland operates a TSH-based CH screening programme, which does not detect CeCH; therefore, genetic ascertainment preceded biochemical diagnosis of moderate CH in five of seven boys as well as their 75-year-old grandfather. Clinical features potentially attributable to hypothyroidism were variable; normal free T3 (FT3) and low/low normal reverse T3 (rT3) concentrations suggested that preferential deiodination of FT4 to FT3 may help maintain tissue euthyroidism in some individuals. However, neonatal jaundice, delayed speech or growth, and obesity were observed in seven subjects in whom diagnosis was delayed. CONCLUSIONS: As observed with other IGSF1 mutations, p.L773P results in variably penetrant IGSF1 deficiency syndrome. Our observations emphasize the need for multi-generation genetic ascertainment in affected families, especially where TSH-based CH screening programmes may fail to detect CeCH at birth.

Evaluation of growth hormone stimulation testing in children.

OBJECTIVE: To evaluate the use and interpretation of growth hormone (GH) stimulation tests used across the UK for diagnosing GH deficiency. BACKGROUND: Previous studies show poor consensus on the use of GH stimulation tests. Sex steroid priming and retesting in the transition period are areas not previously surveyed. DESIGN: Data were collected from tertiary paediatric endocrinologists, paediatricians with a specialist interest in endocrinology and biochemists across the UK over 6 months through distributing electronic surveys. RESULTS: At least three different GH stimulation tests were used by 33% of departments. Glucagon and insulin doses varied most, and sampling frequency varied most using insulin. All laboratories use a recommended chemiluminescence immunoassay with an acceptable coefficient of variability. The GH peak for diagnosing GH deficiency varied from 6 to 8 µg/l. A wide range of clinical scenarios prompted retesting in the transition period, suggesting nonstandardized current practice. Seventy-five per cent of departments use sex steroid priming, but follow criteria variously combining bone age, chronological age and pubertal stage, together with variations in steroid type and dose. CONCLUSIONS: Although a contentious diagnostic test, GH stimulation tests remain the gold standard for diagnosing GH deficiency. Our data suggest that together with variation in indication, protocol and interpretation, there is considerable variation in current practices pertaining to priming and retesting in transition. Given the current financial climate and the need for careful resource management, this study emphasizes the considerable need for consensus in the investigation, diagnosis and long-term follow-up of these children, at least nationally if not internationally.

HESX1 mutations in patients with congenital hypopituitarism: variable phenotypes with the same genotype.

INTRODUCTION: Mutations in the transcription factor HESX1 can cause isolated growth hormone deficiency (IGHD) or combined pituitary hormone deficiency (CPHD) with or without septo-optic dysplasia (SOD). So far there is no clear genotype-phenotype correlation. PATIENTS AND RESULTS: We report four different recessive loss-of-function mutations in three unrelated families with CPHD and no midline defects or SOD. A homozygous p.R160C mutation was found by Sanger sequencing in two siblings from a consanguineous family. These patients presented with ACTH, TSH and GH deficiencies, severe anterior pituitary hypoplasia (APH) or pituitary aplasia (PA) and normal posterior pituitary. The p.R160C mutation was previously reported in a case with SOD, CPHD and ectopic posterior pituitary (EPP). Using exome sequencing, a homozygous p.I26T mutation was found in a Brazilian patient born to consanguineous parents. This patient had evolving CPHD, normal ACTH, APH and normal posterior pituitary (NPP). A previously reported patient homozygous for p.I26T had evolving CPHD and EPP. Finally, we identified compound heterozygous mutations in HESX1, p.[R159W];[R160H], in a patient with PA and CPHD. We showed that both of these mutations abrogate the ability of HESX1 to repress PROP1-mediated transcriptional activation. A patient homozygous for p.R160H was previously reported in a patient with CPHD, EPP, APH. CONCLUSION: These three examples demonstrate that HESX1 mutations cause variable clinical features in patients, which suggests an influence of modifier genes or environmental factors on the phenotype.

Management of Cushing syndrome in children and adolescents: experience of a single tertiary centre.

UNLABELLED: The diagnosis and management of paediatric Cushing syndrome (CS) is highly challenging. This study aims to characterise its presentation, diagnosis, management and outcome by a retrospective case review of 30 patients (14 females) followed at a single tertiary paediatric endocrinology centre over a 30-year period. At presentation, median age was 8.9 years (0.2-15.5) and the commonest manifestations were weight gain (23/30), hirsutism (17/30), acne (15/30) and hypertension (15/30). Growth retardation was present in 11/30. Median body mass index (BMI) was +2.1 standard deviation score (SDS) (-6.5 to +4.6). Urinary free cortisol (UFC) was abnormal in 17/18 (94 %), midnight cortisol in 27/27 (100 %) and low-dose dexamethasone suppression (LDDS) test in 20/20 (100 %). High-dose dexamethasone suppression (HDDS) test was abnormal in 6/6 (100 %) of adrenal tumours, 1/10 (10 %) of Cushing disease (CD) and 1/2 (50 %) of ectopic tumours. Bilateral inferior petrosal sinus sampling (IPSS) identified five CD cases and one ectopic tumour. All patients underwent surgery and subsequently required cortisol replacement. Final diagnoses were 16 CD, 11 adrenal disease, 2 ectopic ACTH-secreting lesions and 1 case of unidentified aetiology. One year post-diagnosis, median BMI was 0.5 SDS (-2.5 to +3.7), hypertension was present in 4/14 (28 %), and 43 % (12/30) of individuals were off hydrocortisone. CONCLUSION: The prevalence of the clinical manifestations differs from that reported in other series. Screening tests were highly sensitive, with UFC, midnight cortisol and LDDS performing well. One year post-treatment, BMI and BP normalised in the majority of patients and almost half of them were able to discontinue replacement hydrocortisone. WHAT IS KNOWN: •Cushing syndrome is an extremely rare entity in the paediatric and adolescent age groups, so not many cohort studies have been published in this population. •Several tests can be employed to firstly diagnose hypercortisolaemia and secondly identify the source of origin of it. The efficacy and safety of these tests in children is still uncertain. What is New: •This study includes cases due to the different aetiologies of endogenous hypercortisolaemia (pituitary, adrenal and ectopic hypercortisolaemia) allowing us to compare the differences in presentation, diagnosis, management and long-term outcome between the groups. •There is a difference in the prevalence of Cushing syndrome symptoms and in the performance of the tests in our cohort compared to previously published studies in the literature.

Neuropathy target esterase impairments cause Oliver-McFarlane and Laurence-Moon syndromes.

BACKGROUND: Oliver-McFarlane syndrome is characterised by trichomegaly, congenital hypopituitarism and retinal degeneration with choroidal atrophy. Laurence-Moon syndrome presents similarly, though with progressive spinocerebellar ataxia and spastic paraplegia and without trichomegaly. Both recessively inherited disorders have no known genetic cause. METHODS: Whole-exome sequencing was performed to identify the genetic causes of these disorders. Mutations were functionally validated in zebrafish pnpla6 morphants. Embryonic expression was evaluated via in situ hybridisation in human embryonic sections. Human neurohistopathology was performed to characterise cerebellar degeneration. Enzymatic activities were measured in patient-derived fibroblast cell lines. RESULTS: Eight mutations in six families with Oliver-McFarlane or Laurence-Moon syndrome were identified in the PNPLA6 gene, which encodes neuropathy target esterase (NTE). PNPLA6 expression was found in the developing human eye, pituitary and brain. In zebrafish, the pnpla6 curly-tailed morphant phenotype was fully rescued by wild-type human PNPLA6 mRNA and not by mutation-harbouring mRNAs. NTE enzymatic activity was significantly reduced in fibroblast cells derived from individuals with Oliver-McFarlane syndrome. Intriguingly, adult brain histology from a patient with highly overlapping features of Oliver-McFarlane and Laurence-Moon syndromes revealed extensive cerebellar degeneration and atrophy. CONCLUSIONS: Previously, PNPLA6 mutations have been associated with spastic paraplegia type 39, Gordon-Holmes syndrome and Boucher-Neuhäuser syndromes. Discovery of these additional PNPLA6-opathies further elucidates a spectrum of neurodevelopmental and neurodegenerative disorders associated with NTE impairment and suggests a unifying mechanism with diagnostic and prognostic importance.