To explore genetic basis leading to meiotic disruption in human gametogenesis via exome sequencing. This study included three consanguineous families with well-defined infertility phenotypes. Exome sequencing was performed for the index case in family 1 and for the trio (index with parents) in the other two families. Sanger sequencing was used for confirmation and family segregation analysis. Exome sequencing revealed homozygous loss-of-function variations in SPIDR, TOP6BL, and RAD51AP2 in families 1, 2, and 3, respectively. Segregation in individual families revealed that the parents were carriers, as were the fertile siblings in families 1 and 2. All three genes function in double-strand break formation or repair, identified variants may therefore impair, potentially preventing its completion and contributing to infertility in the index cases. Gene-disease relationships (GDR) were re-evaluated due to the addition of new patients and/or variants in the literature. Our findings provide additional evidence for the role of SPIDR, TOP6BL, and RAD51AP2 as genetic contributors to human infertility due to meiotic errors. For patients with a similar phenotype, genetic screening could be recommended, and the identification of pathogenic variations might help avoid unsuccessful fertility treatments. Additionally, in patients with molecular defects in DNA repair genes, chromosomal instability may increase the risk of cancer; therefore, long-term follow-up by a multidisciplinary team is recommended.

Pathogenic variants in the growth hormone releasing hormone receptor (GHRHR) gene cause severe isolated growth hormone deficiency (IGHD). Over 82 distinct variants have been described, mostly in South and East Asia and Northern Brazil. This study characterizes the phenotypic and genotypic variability of children harboring (likely) pathogenic GHRHR variants, included in the Belgian and Luxembourg Registry for Growth Hormone Treated Children. We retrospectively reviewed clinical, biochemical, genetic and neuroimaging data from seven children with severe IGHD carrying biallelic GHRHR variants. Peak growth hormone (GH) concentrations were measured following insulin and glucagon-induced hypoglycemia. Auxological parameters at diagnosis and pituitary magnetic resonance imaging (MRI) findings were obtained from medical records. Three children of Syrian origin from two consanguineous families carried a novel likely pathogenic c.367G > T, p.(Glu123*) variant in a homozygous state. Among the four Belgian-origin patients, one was homozygous for a pathogenic c.674_677delinsGCTGTTGGCAGAAG, p.(Val225Gly*fs165) variant, while two siblings were compound heterozygous including this particular variant and an additional pathogenic c.271dupG, p.(Ala91Glyfs*13) frameshift variant. The other Belgian patient was compound heterozygous for the well described likely pathogenic c.431 T > A, p.(Leu144His) variant and a previously undescribed c.150C > A, p.(Asn50Lys) variant. IGHD was diagnosed between 7 months and 7 years. Height SDS at presentation ranged from − 4.6 to − 3.4. Peak GH levels after stimulation were markedly reduced (0.35–3.4 ng/ml), confirming severe growth hormone deficiency (GHD). No dysmorphic features were observed. Anterior pituitary hypoplasia at MRI was seen in six patients. Conclusion: This series expands the geographic spectrum of biallelic GHRHR variants causing severe IGHD. Targeted GHRHR genotyping should be considered in children with early-onset severe IGHD, particularly when anterior pituitary hypoplasia is present and dysmorphic features are absent.

INTRODUCTION:Since the first description of Turner syndrome (TS), both genotypic spectrum and phenotypic presentation have evolved. This study aimed to examine trends in this evolution over the past three decades and provides an overview of current genetic and clinical features in a large nationwide multicenter cohort of girls with TS. METHODS:We analyzed data from growth hormone (GH)-treated girls with TS included in BELGROW, the national GH registry of the BELux Society for Pediatric Endocrinology and Diabetology, between 1985 and 2022. Karyotype, age at diagnosis, and phenotype were studied in 716 girls. Two periods were compared: 1991-2002 (group 1, n = 250) and 2003-2017 (group 2, n = 270). RESULTS:The annual number of girls with TS starting GH remained stable (mean n = 19/year). In the entire cohort, monosomy 45,X was the most frequent karyotype (44%), followed by structural anomalies of the X chromosome (27%), 45,X/46,XX mosaicism (13%), triple X mosaicism (4%), 45,X/46,XY or complex Y anomalies (6%), and others (6%). The proportion of 45,X decreased between the two periods (46%-38%, p < 0.05). Overall, median age at diagnosis was 6.4 years with 7.6% of girls diagnosed prenatally, 24% before age 1, 49% in childhood, and 19% after 12 years. Prenatal diagnoses increased from 2.5% (group 1) to 15% (group 2) (p < 0.001). Girls with a 45,X karyotype were diagnosed earlier than girls with other genotypes (median 2.2 vs. 8 years, p < 0.001). Skeletal (73%), neurosensory (60%), and cardiac (29%) systems were most affected. Skeletal and cardiac malformations were more frequent in girls with a 45,X karyotype (p < 0.05 and p < 0.01, respectively). CONCLUSION:Genotype distribution and timing of TS diagnosis have significantly changed since 1991, while the annual number of girls starting GH therapy has remained stable. A 45,X karyotype is associated with earlier diagnosis and more comorbidities.

This study aimed to assess the thiamazole sales in the paediatric population in Belgium from 2016 to 2023 in Belgium using the data f provided by The National Institute for Health and Disability Insurance (NIHDI). It also assessed during the same period the number of pediatric patients diagnosed with pediatric AITD in a single-center setting. We retrospectively analyzed data from the NIHDI national database, collecting the daily defined dose (DDD) and the number of pediatric patients treated with thiamazole. Additionally, a single-center study was conducted including children newly diagnosed HT or GD between January 1, 2016, and December 31, 2023. Patients were categorized into three groups: pre-pandemic (2016–2019), pandemic (2020–2022), and post-pandemic (2023). An increase in thiamazole prescriptions was observed, peaking in 2022 (88,500 DDD/year for Group 2 vs. 77,295 DDD/year for Group 1, p = 0.001). At our center, among the 43 newly diagnosed patients with GD, a significant rise in GD diagnoses was noted during the pandemic (10 cases/year) compared to the pre- and post-pandemic periods (3 cases/year, p = 0.037). In contrast, the number of HT cases remained stable across all three periods, with a total of 141 patients. No significant differences in disease severity were found between patients diagnosed before or during the pandemic. Pediatric thiamazole prescriptions at the national level and GD diagnoses at the local level increased during the COVID-19 pandemic, while HT incidence remained unchanged. Although a direct causal link with SARS-CoV-2 cannot be confirmed, these findings suggest that the pandemic may have influenced GD incidence, warranting further investigation. Disease severity did not differ between patients diagnosed before and during the pandemic.

Background: Newborn screening for congenital hypothyroidism (CH) has been implemented in high-income countries since the 1970s to prevent intellectual disability. A delayed thyrotropin (TSH) rise with a normal TSH on the first dry blood spot (DBS) sample, followed by an abnormal TSH on the subsequent DBS, is sometimes observed in preterm newborns. The incidence of permanent CH and the screening process in preterm newborns remain controversial. Our aim was to evaluate the incidence of transient and permanent CH and delayed TSH rise in preterm newborns. The utility of a multiple screening samples is discussed. Methods: We conducted a retrospective study on preterm newborns (<37 weeks of gestation) screened at the Newborn Screening Center of Université Libre de Bruxelles between January 2014 and December 2023. A literature review was performed to identify cases of permanent CH with delayed TSH rise in cohorts of preterm newborns. Results: Of the 3578 preterm newborns included in the study, 10 were diagnosed with CH (0.3%). The majority of CH cases were transient (6 out of 10 transient, one deceased and one under ongoing L-thyroxine, too young for weaning attempt). Six cases were detected at the first DBS, four at subsequent DBS. Only two cases were confirmed as permanent CH, yielding an incidence of 1 in 1789 for permanent CH in preterms (0.05%). One of the two had a delayed TSH rise. Genetic testing helped in establishing the diagnosis of permanent CH with gland in situ. Conclusions: Permanent CH appears to be rarer than transient CH among preterm newborns (1/1789 vs. 1/596). Transient CH may be suspected in case of iodine exposure or thyroid ultrasound showing an in situ gland with negative genetic testing and absent maternal blocking antibodies. In such cases, early L-thyroxine weaning may help avoid overtreatment. A delayed TSH rise leading to a false negative first DBS is not uncommon in preterm newborns with permanent CH. This justifies a second DBS in preterms. Given the retrospective nature of this study, these findings should be interpreted with caution, and further prospective research is warranted to confirm these observations.

Objective:A secular trend toward earlier puberty onset in girls has been widely documented, with childhood overweight proposed as a contributing risk factor. This study aims to characterize body mass index (BMI) standard deviation score (SDS) trajectories over the 6 years preceding idiopathic central precocious puberty (CPP) onset in girls. Design and methods:This retrospective, single-center study included 460 girls diagnosed with idiopathic CPP at the Academic Children's Hospital Queen Fabiola between 2002 and 2022. The cohort was stratified into sporadic CPP, familial CPP, and CPP in internationally adopted girls. Clinical and demographic data were collected, and BMI trajectories were analyzed using piecewise mixed linear models. Pubertal onset (T0) was defined as Tanner stage B2. Results:Among the 460 cases, 285 (62%) were sporadic, 145 (31.5%) familial, and 30 (6.5%) adoption-related CPP. In addition, 11.7% were born small for gestational age (SGA). BMI SDS increased significantly during the 6 years preceding T0 across the entire cohort. The steepest rise occurred between 6 and 3 years before T0 (+0.21 SDS/year (95% CI: 0.13-0.29)), followed by a slower increase in the 3 years before T0 (+0.15 SDS/year (95% CI: 0.11-0.19)), and a subsequent stabilization post-T0 (+0.06 SDS/year (95% CI: -0.01-0.14)). The BMI increase rate was similar across all subgroups. Conclusions:Girls with idiopathic CPP show a significant prepubertal BMI SDS increase, with similar trajectories in sporadic and familial cases. The overrepresentation of SGA-born and adopted girls suggests that genetic and environmental factors may contribute to early pubertal onset. Plain language summary:This study is the first to track BMI trajectories up to 6 years before idiopathic CPP onset in girls, revealing an early rise in BMI SDS across all subgroups (sporadic, familial, and adopted girls). Notably, SGA-born and adopted girls showed similar BMI patterns but were overrepresented in this CPP cohort.

Next generation sequencing has revolutionized the diagnostic approach for patients with neurodevelopmental disorders (NDDs), yields are however highly variable depending on the patient's phenotype. It is often challenging to predict which indications are likely to lead to a molecular diagnosis and which will benefit less from genetic testing. To identify phenotypic characteristics associated with higher diagnostic yields we conducted detailed phenotyping of a cohort of 868 children with NDD, who underwent clinical exome sequencing between 2016 and 2021. A molecular diagnosis was reached in 27 % of cases. Significantly higher yields of respectively 34 % and 32 % were observed in patients with intellectual disability (ID) or global developmental delay (GDD). Autism spectrum disorders (ASD) were less likely to result in a molecular diagnosis with a diagnostic yield of 16 %. Additional factors linked to higher yields included female gender, the presence of minor dysmorphic features - particularly involving the face, extremities, ears, eyes, and hair - and a syndromic phenotype. Additional CNV calling in a subset of 438 patients which consented to reanalysis of sequencing data added 1.5 % to diagnostic yield.

OBJECTIVE:Adrenal cortisol production occurs through a biosynthetic pathway which depend on NADH and NADPH for energy supply. The mitochondrial respiratory chain and the reactive oxygen species (ROS) detoxification system are therefore important for steroidogenesis. Mitochondrial dysfunction leading to oxidative stress has been implicated in the pathogenesis of several adrenal conditions. Nonetheless, only very few patients with variants in one gene of the ROS detoxification system, Thioredoxin Reductase 2 (TXNRD2), have been described with variable phenotypes. DESIGN:Clinical, genetic, structural, and functional characterization of a novel, biallelic TXNRD2 splice variant. METHODS:On human biomaterial, we performed whole exome sequencing to identify and RNA analysis to characterize the specific TXNRD2 splice variant. Amino acid conservation analysis and protein structure modeling were performed in silico. Using patient's fibroblast-derived human induced pluripotent stem cells, we generated adrenal-like cells (iALC) to study the impact of wild-type (WT) and mutant TXNRD2 on adrenal steroidogenesis and ROS production. RESULTS:The patient had a complex phenotype of primary adrenal insufficiency (PAI), combined with genital, ophthalmological, and neurological features. He carried a homozygous splice variant c.1348-1G > T in TXNRD2 which leads to a shorter protein lacking the C-terminus and thereby affecting homodimerization and flavin adenine dinucleotide binding. Patient-derived iALC showed a loss of cortisol production with overall diminished adrenal steroidogenesis, while ROS production was significantly increased. CONCLUSION:Lack of TXNRD2 activity for mitochondrial ROS detoxification affects adrenal steroidogenesis and predominantly cortisol production.

IntroductionCraniopharyngiomas (CPs) are benign brain tumors accounting for 5 - 11% of intracranial tumors in children. These tumors often recur and can cause severe morbidity. Postoperative radiotherapy efficiently controls and prevents progression and recurrence. Despite advancements in neurosurgery, endocrinological, visual, and neuropsychological complications are common and significantly lower the quality of life of patients.MethodsWe performed a retrospective study, including all patients younger than sixteen diagnosed with CP between July 1989 and August 2022 and followed up in Hôpital Universitaire de Bruxelles.ResultsNineteen children with CP were included, with median age of 7 years at first symptoms and 7.5 at diagnosis. Common symptoms at diagnosis were increased intracranial pressure (63%), visual impairment (47%), growth failure (26%), polyuria/polydipsia (16%), and weight gain (10.5%). As clinical signs at diagnosis, growth failure was observed in 11/18 patients, starting with a median lag of 1 year and 4 months before diagnosis. On ophthalmological examination, 27% of patients had papillary edema and 79% had visual impairment. When visual disturbances were found, the average preoperative volume was higher (p=0.039). Only 6/19 patients had gross total surgical resection. After the first neurosurgery, 83% experienced tumor recurrence or progression at a median time of 22 months. Eleven patients (73%) underwent postsurgical radiotherapy. At diagnosis, growth hormone deficiency (GHD) was the most frequent endocrine deficit (8/17) and one year post surgery, AVP deficiency was the most frequent deficit (14/17). Obesity was present in 13% of patients at diagnosis, and in 40% six months after surgery. There was no significant change in body mass index over time (p=0.273) after the first six months post-surgery.ConclusionCP is a challenging brain tumor that requires multimodal therapy and lifelong multidisciplinary follow-up including hormonal substitution therapy. Early recognition of symptoms is crucial for prompt surgical management. The management of long-term sequelae and morbidity are crucial parts of the clinical path of the patients. The results of this study highlight the fundamental importance of carrying out a complete assessment (ophthalmological, endocrinological, neurocognitive) at the time of diagnosis and during follow-up so that patients can benefit from the best possible care.

La surcharge iodée peut être responsable d'une hypothyroïdie chez le nouveau-né via l'effet Wolff-Chaikoff. Ceci peut être consécutif à l'utilisation de produits iodés chez le bébé ou chez la femme enceinte ou allaitante. Actuellement, en Belgique, il existe encore de nombreuses utilisations de produits iodés pendant la grossesse, lors de l'accouchement et chez le jeune nourrisson, malgré la connaissance depuis les années 1980 de l'effet inhibiteur de l'iode sur la fonction thyroïdienne. L'objet de cette revue narrative de la littérature est de revoir les bases de la physiologie thyroïdienne et d'exposer les preuves de l'effet délétère d'une surcharge iodée sur la fonction thyroïdienne chez le nouveau-né. Pour illustrer le propos, nous rapportons le cas d'un garçon ayant présenté une TSH très élevée au dépistage (213 mU/L au troisième jour de vie) et une glande thyroïde in situ non goitreuse, sans étiologie génétique. Un antiseptique iodé a été utilisé chez la mère suite à une épisiotomie. L'enfant a bénéficié d'un traitement par Lévothyroxine dont la dose journalière n'a pas dû être augmentée malgré la croissance de l'enfant. A deux ans et demi, la Lévothyroxine a pu être interrompue. La fonction thyroïdienne, la croissance et le développement de l'enfant sont normaux jusqu'au dernier contact à l'âge de 6 ans. Nous concluons donc à une surcharge iodée chez la mère allaitante causant une hypothyroïdie transitoire chez son bébé.

Biallelic loss-of-function variants in the IYD gene cause hypothyroidism resulting from iodine wasting. We describe 8 patients (from 4 families in which the parents are first cousins) who are homozygous for a variant in IYD (including a novel missense deleterious variant, c.791C>T [P264L], in 1 family). Seven patients presented between 5 and 16 years of age with a large goiter, overt hypothyroidism, and a high serum thyroglobulin. The goiter subsided with levothyroxine therapy in most. Upon stopping levothyroxine in 5 patients, goiter and hypothyroidism reappeared in 3. In these 3 patients, a rising serum thyroglobulin concentration preceded hypothyroidism and goiter and urinary iodine excretion was low. In patients who remained euthyroid, urinary iodine was normal. In conclusion, these patients bearing biallelic pathogenic variants in IYD developed a large goiter, a high serum thyroglobulin, and overt hypothyroidism when their iodine intake was low.

Objective: Until November 2019 in Belgium, dried blood spot (DBS) sampling was performed between 72 and 120 hours of life, when a majority of newborns had already been discharged from the maternity. In November 2019, the policy for newborn screening in South Belgium changed to allow sampling as soon as 48 hours of life, with the objective to accelerate the process and to allow more sampling during the hospital stay. Our objective was to evaluate the impact of this policy modification and, in particular, to assess the effectiveness of screening for hypothyroidism based on sampling before or after 72 hours of life, as well as to compare the effectiveness of DBS collection before discharge or at home. Methods: This retrospective study included live births ≥37 weeks of gestation, screened by the Université Libre de Bruxelles Newborn Screening Center between January 2019 and December 2021. To evaluate the efficiency of early sampling, we compared thyrotropin (TSH) results for screening <72 hours and screening ≥72 hours. We also compared TSH results of DBS performed before discharge with those performed at home. Results: A total of 53,794 newborns were included. The results of 24,816 healthy newborns screened before 72 hours of life and of 28,978 healthy newborns screened between 72 and 144 hours of life were compared. The median TSH level was similar (1.50 and 1.20 mU/L, respectively). The percentage of false positives was similar (0.08% and 0.07%, respectively). Earlier sampling, before 72 hours, allowed treatment of positive cases at 6 days rather than 8.5 days. DBS sampling at home resulted in longer delay for transferring the sample to the laboratory (a median of 3.0 days for hospital sampling vs. 5.0 days for home sampling). A poorer quality of home blood sampling was observed, with 0.27% unusable samples compared with 0.06% unusable samples for hospital sampling (p < 0.001). Conclusions: In term newborns, TSH screening before discharge, as early as 48 hours of life, is a valid strategy. It allows earlier treatment of positive cases, does not increase the percentage of false positives, and results in fewer unusable samples.

STUDY QUESTION:What is the long-term outcome of individuals born with bilateral testicular regression (BTR) in relation to its underlying etiology? SUMMARY ANSWER:Statural growth and pubertal development are adequate with incremental doses of testosterone replacement therapy (TRT); however, penile growth is often suboptimal, especially in those with a suspected genetic etiology (i.e. heterozygous DHX37 variants) or a micropenis at birth. WHAT IS KNOWN ALREADY:BTR is a rare and poorly understood condition. Although a vascular origin has been postulated, heterozygous missense variants in DHX37 have been attributed to the phenotype as well. How these various etiologies impact the clinical phenotype, gonadal histology and outcome of BTR remains unclear. STUDY DESIGN SIZE DURATION:For this cross-sectional study, individuals with BTR were recruited in eight Belgian pediatric endocrinology departments, between December 2019 and December 2022. A physical exam was performed cross-sectionally in all 17 end-pubertal participants and a quality of care questionnaire was completed by 11 of them. Exome-based panel testing of 241 genes involved in gonadal development and spermatogenesis was performed along with a retrospective analysis of presentation and management. A centralized histological review of gonadal rests was done for 10 participants. PARTICIPANTS/MATERIALS SETTING METHODS:A total of 35 participants (33 with male, 1 with female, and 1 with non-binary gender identity) were recruited at a mean age of 15.0 ± 5.7 years. MAIN RESULTS AND THE ROLE OF CHANCE:The median age at presentation was 1.2 years [0-14 years]. Maternal gestational complications were common (38.2%), with a notably high incidence of monozygotic twin pregnancies (8.8%). Heterozygous (likely) pathogenic missense variants in DHX37 (p.Arg334Trp and p.Arg308Gln) were found in three participants. No other (likely) pathogenic variants were found. All three participants with a DHX37 variant had a microphallus at birth (leading to female sex assignment in one), while only six of the remaining 31 participants without a DHX37 variant (19.4%) had a microphallus at birth (information regarding one participant was missing). Testosterone therapy during infancy to increase penile growth was more effective in those without versus those with a DHX37 variant. The three participants with a DHX37 variant developed a male, female, and non-binary gender identity, respectively; all other participants identified as males. TRT in incremental doses had been initiated in 25 participants (median age at start was 12.4 years). Final height was within the target height range in all end-pubertal participants; however, 5 out of 11 participants (45.5%), for whom stretched penile length (SPL) was measured, had a micropenis (mean adult SPL: 9.6 ± 2.5). Of the 11 participants who completed the questionnaire, five (45.5%) reported suboptimal understanding of the goals and effects of TRT at the time of puberty induction. Furthermore, only 6 (54.5%) and 5 (45.5%) of these 11 participants indicated that they were well informed about the risks and potential side effects of TRT, respectively. Histological analysis of two participants with DHX37 variants suggested early disruption of gonadal development due to the presence of Müllerian remnants in both and undifferentiated gonadal tissue in one. In eight other analyzed participants, no gonadal remnants were found, in line with the BTR diagnosis. LIMITATIONS REASONS FOR CAUTION:The limitations of this study include the relatively small sample size (n = 35) and the few individuals with DHX37 variants (n = 3). Furthermore, data on the SPL were often missing, due to this being undocumented or refused by participants. WIDER IMPLICATIONS OF THE FINDINGS:TRT provides adequate statural growth, even when initiated in late adolescence, thus providing time for physicians to explore the patients' gender identity if needed. However, sufficient and understandable information regarding the effects and side effects of TRT is required throughout the management of these patients. SPL remains suboptimal in many individuals and could be improved by TRT during infancy to mimic the physiological mini-puberty. An environmental origin in some participants is supported by the high incidence of gestational complications (38.2%) and by the three monozygotic twin pregnancies discordant for the BTR phenotype. Individuals with a heterozygous DHX37 variant have a more severe phenotype with severely restricted penile growth until adulthood. Histological analysis confirmed DHX37 as a gonadal development, rather than a BTR-related, gene. STUDY FUNDING/COMPETING INTERESTS:Funding was provided by the Belgian Society for Pediatric Endocrinology and Diabetology (BESPEED) and by Ghent University Hospital under the NucleUZ Grant (E.D.B.). M.C. and E.D.B. are supported by an FWO senior clinical investigator grant (1801018N and 1802220N, respectively). The authors report no conflicts of interest. TRIAL REGISTRATION NUMBER:N/A.