An animal model for Pierpont syndrome: a mouse bearing the Tbl1xr1Y446C/Y446C mutation.

Pierpont syndrome is a rare disorder characterized mainly by global developmental delay, unusual facial features, altered fat distribution in the limbs and hearing loss. A specific mutation (p.Tyr446Cys) in TBL1XR1, encoding a WD40 repeat-containing protein, which is a component of the SMRT/NCoR (silencing mediator retinoid and thyroid hormone receptors/nuclear receptor corepressors), has been reported as the genetic cause of Pierpont syndrome. Here, we used CRISPR-cas9 technology to generate a mutant mouse with the Y446C mutation in Tbl1xr1, which is also present in Pierpont syndrome. Several aspects of the phenotype were studied in the mutant mice: growth, body composition, hearing, motor behavior, thyroid hormone state and lipid and glucose metabolism. The mutant mice (Tbl1xr1Y446C/Y446C) displayed delayed growth, altered body composition with increased relative lean mass and impaired hearing. Expression of several genes involved in fatty acid metabolism differed in white adipose tissue, but not in liver or muscle of mutant mice compared to wild-type mice (Tbl1xr1+/+). No difference in thyroid hormone plasma concentrations was observed. Tbl1xr1Y446C/Y446C mice can be used as a model for distinct features of Pierpont syndrome, which will enable future studies on the pathogenic mechanisms underlying the various phenotypic characteristics.

Genetics of Primary Congenital Hypothyroidism.

Congenital hypothyroidism (CH) is one of the most common preventable forms of mental retardation and since the implementation of neonatal screening programs in the mid-1970s, early detection and treatment have proven to be very successful in preventing brain damage. CH may be of thyroidal (= primary) or of hypothalamic-pituitary (= central) origin. Primary CH may be due to abnormal thyroid gland formation (dysgenesis) or defective thyroid hormone syntheses by a structurally normal gland (dyshormonogenesis). While thyroid dysgenesis is the most common form of CH, accounting for approximately 85% of cases, genetic defects are only found in a very low proportion of patients. On the other hand, thyroid dyshormonogenesis is less common, but is usually a genetic condition with autosomal recessive inheritance. In this review we provide an overview of all known monogenetic causes of primary CH, including promising new candidate genes. In addition, alternative genetic mechanisms are discussed.

Analysis of genes differentially expressed in the cortex of mice with the Tbl1xr1Y446C/Y446C variant.

Transducin ß-like 1 X-linked receptor 1 (mouse Tbl1xr1) or TBL1X/Y related 1 (human TBL1XR1), part of the NCoR/SMRT corepressor complex, is involved in nuclear receptor signaling. Variants in TBL1XR1 cause a variety of neurodevelopmental disorders including Pierpont syndrome caused by the p.Tyr446Cys variant. We recently reported a mouse model carrying the Tbl1xr1Y446C/Y446C variant as a model for Pierpont syndrome. To obtain insight into mechanisms involved in altered brain development we studied gene expression patterns in the cortex of mutant and wild type (WT) mice, using RNA-sequencing, differentially expressed gene (DEG) analysis, gene set enrichment analysis (GSEA), weighted gene correlation network analysis (WGCNA) and hub gene analysis. We validated results in mutated mouse cortex, as well as in BV2 and SK-N-AS cell lines, in both of which Tbl1xr1 was knocked down by siRNA. Two DEGs (adj.P. Val < 0.05) were found in the cortex, Mpeg1 (downregulated in mutant mice) and 2900052N01Rik (upregulated in mutant mice). GSEA, WGCNA and hub gene analysis demonstrated changes in genes involved in ion channel function and neuroinflammation in the cortex of the Tbl1xr1Y446C/Y446C mice. The lowered expression of ion channel genes Kcnh3 and Kcnj4 mRNA was validated in the mutant mouse cortex, and increased expression of TRIM9, associated with neuroinflammation, was confirmed in the SK-N-AS cell line. Conclusively, our results show altered expression of genes involved in ion channel function and neuroinflammation in the cortex of the Tbl1xr1Y446C/Y446C mice. These may partly explain the impaired neurodevelopment observed in individuals with Pierpont syndrome and related TBL1XR1-related disorders.

Mutant Tbl1x male mice have a short life span and do not breed: unexpected findings.

Humans with the mutation Y509C in transducin beta like 1 X-linked (TBL1X HGNC ID HGNC:11585) have been reported to present with the combination of central congenital hypothyroidism and impaired hearing. TBL1X belongs to the WD40 repeat-containing protein family, is part of NCoR and SMRT corepressor complexes, and thereby involved in thyroid hormone signaling. In order to investigate the effects of the Y509C mutation in TBL1X on cellular thyroid hormone action, we aimed to generate a hemizygous male mouse cohort carrying the Tbl1x Y459C mutation which is equivalent to the human TBL1X Y509C mutation using CRISPR/Cas9 technology. Hemizygous male mice were small at birth and inactive. Their life span (median life span 93 days) was very short compared with heterozygous female mice (survived to >200 days with no welfare issues). About 52% of mice did not survive to weaning (133 mice). Of the remaining 118 mice, only 8 were hemizygous males who were unable to mate whereby it was impossible to generate homozygous female mice. In conclusion, the Tbl1x Y459C mutation in male mice has a marked negative effect on birth weight, survival, and fertility of male mice. The present findings are unexpected as they are in contrast to the mild phenotype in human males carrying the equivalent TBL1X Y509C mutation.

Pediatric Graves' orbitopathy: a multicentre study.

PURPOSE: Graves' orbitopathy (GO) is a rare condition in children often considered to be a less severe condition than at an older age. The aim of our study was to analyse if there are any factors that distinguish paediatric from adult GO in order to provide guidelines for assessing and managing paediatric GO. METHODS: Study design is a multicentre retrospective observational case series; 115 paediatric patients diagnosed with GO who visited our university medical centres in the Netherlands and Iran between 2003 and 2019 were submitted for complete ophthalmological examinations, serological testing and/or orbital imaging. Main outcome measures focussed on the natural course and clinical picture as well as medical and surgical treatment in paediatric GO. RESULTS: Clinical findings included proptosis (n = 97; 84.3%), eyelid retraction (n = 77; 67%) and diplopia (n = 13; 11.3%). Ninety-two patients (80%) presented with mild disease, 21 (18.3%) with moderate-severe disease and two (1.7%) with severe GO. Five patients (4.3%) underwent intravenous glucocorticoids and 25 patients underwent orbital decompression surgery. Strabismus surgery due to primary involvement of extraocular muscles was performed in two patients (1.7%). Overall, rehabilitative surgical treatment was planned in 31 patients (26.9%) with inactive disease. Two patients experienced reactivation of the disease. CONCLUSION: Despite the fact that paediatric and adult GO are considered two separate entities, they might be the same disease with two different clinical phenotypes. Paediatric GO population presents with a comparable clinical picture regarding both soft tissue involvement and proptosis, which may require surgical intervention. Proptosis was present in the majority of paediatric GO patients. Orbital decompression was performed in 21.7% of patients.

Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology.

Background: An ENDO-European Reference Network (ERN) initiative was launched that was endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology with 22 participants from the ENDO-ERN and the two societies. The aim was to update the practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). A systematic literature search was conducted to identify key articles on neonatal screening, diagnosis, and management of primary and central CH. The evidence-based guidelines were graded with the Grading of Recommendations, Assessment, Development and Evaluation system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Summary: The recommendations include the various neonatal screening approaches for CH as well as the etiology (also genetics), diagnostics, treatment, and prognosis of both primary and central CH. When CH is diagnosed, the expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up including laboratory testing to keep thyroid hormone levels in their target ranges, timely assessment of the need to continue treatment, attention for neurodevelopment and neurosensory functions, and, if necessary, consulting other health professionals, and education of the child and family about CH. Harmonization of diagnostics, treatment, and follow-up will optimize patient outcomes. Lastly, all individuals with CH are entitled to a well-planned transition of care from pediatrics to adult medicine. Conclusions: This consensus guidelines update should be used to further optimize detection, diagnosis, treatment, and follow-up of children with all forms of CH in the light of the most recent evidence. It should be helpful in convincing health authorities of the benefits of neonatal screening for CH. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition.

High Prevalence of Weight Gain in Childhood Brain Tumor Survivors and Its Association With Hypothalamic-Pituitary Dysfunction.

PURPOSE: Childhood brain tumor survivors (CBTS) are at risk for developing obesity, which negatively influences cardiometabolic health. The prevalence of obesity in CBTS may have been overestimated in previous cohorts because of inclusion of children with craniopharyngioma. On the contrary, the degree of weight gain may have been underestimated because of exclusion of CBTS who experienced weight gain, but were neither overweight nor obese. Weight gain may be an indicator of underlying hypothalamic-pituitary (HP) dysfunction. We aimed to study prevalence of and risk factors for significant weight gain, overweight, or obesity, and its association with HP dysfunction in a national cohort of noncraniopharyngioma and nonpituitary CBTS. METHODS: Prevalence of and risk factors for significant weight gain (body mass index [BMI] change ≥ +2.0 standard deviation score [SDS]), overweight, or obesity at follow-up, and its association with HP dysfunction were studied in a nationwide cohort of CBTS, diagnosed in a 10-year period (2002-2012), excluding all craniopharyngioma and pituitary tumors. RESULTS: Of 661 CBTS, with a median age at follow-up of 7.3 years, 33.1% had significant weight gain, overweight, or obesity. Of the CBTS between 4 and 20 years of age, 28.7% were overweight or obese, compared with 13.2% of the general population between 4 and 20 years of age. BMI SDS at diagnosis, diagnosis of low-grade glioma, diabetes insipidus, and central precocious puberty were associated with weight gain, overweight, or obesity. The prevalence of HP dysfunction was higher in overweight and obese CTBS compared with normal-weight CBTS. CONCLUSION: Overweight, obesity, and significant weight gain are prevalent in CBTS. An increase in BMI during follow-up may be a reflection of HP dysfunction, necessitating more intense endocrine surveillance.

Evaluation of the Dutch neonatal screening for congenital adrenal hyperplasia.

BACKGROUND: In 2002, a nationwide screening for congenital adrenal hyperplasia (CAH) was introduced in the Netherlands. The aim of our study is to evaluate the validity of the neonatal screening for CAH and to assess how many newborns with salt-wasting (SW) CAH have already been clinically diagnosed before the screening result was known. METHODS: Retrospective, descriptive study. The following data of patients with positive screening results since implementation of the screening programme were collected (1 January 2002 up until 31 December 2013): gestational age, sex, diagnosis, clinical presentation and contribution of screening to the diagnosis. RESULTS: In the evaluated period, 2 235 931 newborns were screened. 479 children had an abnormal screening result, 133 children were diagnosed with CAH (114 SW, 14 simple virilizing (SV)), five non-classic CAH. During this period, no patients with SW CAH were missed by neonatal screening (sensitivity was 100%). After exclusion of 17 cases with missing information on diagnosis, specificity was 99.98% and positive predictive value was 24.7%. Most false positives (30%) were attributable to prematurity. Of patients with SW CAH, 68% (71/104) patients were detected by neonatal screening and 33 (33/104) were clinically diagnosed. Of girls with SW CAH, 38% (14/37) were detected by neonatal screening and 62% (23/37) were clinically diagnosed. CONCLUSION: The Dutch neonatal screening has an excellent sensitivity and high specificity. Both boys and girls can benefit from neonatal screening.

Hypothalamic obesity after treatment for craniopharyngioma: the importance of the home environment.

Hypothalamic obesity after treatment for craniopharyngioma is a well-recognized, severe problem. Treatment of hypothalamic obesity is difficult and often frustrating for the patient, the parents and the professional care-giver. Because hypothalamic obesity is caused by an underlying medical disorder, it is often assumed that regular diet and exercise are not beneficial to reduce the extraordinarily high body mass index, and in fact, lifestyle interventions have been shown to be insufficient in case of extreme hypothalamic obesity. Nevertheless, it is important to realize that also in this situation, informal care delivered by the family and appropriate parenting styles are required to minimize the obesity problem. We present a case in which weight gain in the home situation was considered unstoppable, and a very early mortality due to complications of the severe increasing obesity was considered inevitable. A permissive approach toward food intake became leading with rapid weight increase since a restrictive lifestyle was considered a senseless burden for the child. By admission to our hospital for a longer period of time, weight reduction was realized, and the merely permissive approach could be changed into active purposeful care by adequate information, instruction, guidance and encouragement of the affected child and her parents. This case illustrates that, although this type of obesity has a pathological origin, parental and environmental influences remain of extreme importance.

High prevalence of autoimmune thyroiditis in children and adolescents with vitiligo.

BACKGROUND/AIMS: Vitiligo is considered to be an autoimmune disease and is known to be associated with other autoimmune diseases, particularly affecting the thyroid. In children and adolescents this association has been reported in only a few studies, with varying results. The aim of this study was to examine thyroid function and prevalence of thyroid autoimmunity in children and adolescents with vitiligo and to investigate the utility of screening. METHODS: Two hundred and sixty patients with vitiligo were enrolled. Plasma TSH, FT4 and anti-thyroid peroxidase (TPO) antibody concentrations were measured. The prevalence of thyroid dysfunction and autoimmunity were compared to the general healthy paediatric population. RESULTS: Autoimmune thyroiditis (AIT) with thyroid hormone disturbances was diagnosed in 16 patients (6.2%). This is significantly higher than the prevalence reported in the general healthy paediatric population. Increased levels of anti-TPO antibodies (= 30 kU/l), without thyroid hormone disturbances, were found in 27 patients (10.5%). CONCLUSION: The prevalence of AIT in children and adolescents with vitiligo is significantly higher than in the general population. It may be advantageous to screen thyroid function and antibody levels in all paediatric patients with non-segmental vitiligo. To strengthen recommendations on screening, research on the burden for patients and cost-effectiveness is needed.

[Substitution of dexamethasone for dexamphetamine due to their written and spoken similarity]. / Verwisseling dexamfetamine en dexamethason door lees- en klankgelijkenis.

We present a 15-year-old girl and an 11-year-old boy who were prescribed dexamphetamine for treatment of Attention Deficit Hyperactivity Disorder (ADHD), and who subsequently presented with symptoms indicative of Cushing's syndrome. It turned out that both children had taken high doses of dexamethasone instead of dexamphetamine due to an error made by the pharmacist. The diagnosis of exogenous Cushing's syndrome is easily made. However, it is a serious condition with possibly severe and persistent complications. The substitution of dexamethasone for dexamphetamine has been described before. Both doctors and pharmacists should be aware of this possible error.