Introduction: Central precocious puberty (CPP) is rare in boys, and idiopathic forms are particularly uncommon. This study characterizes the genetic architecture of idiopathic CPP (ICPP) in a national cohort of boys. Methods: We conducted a retrospective and prospective study of boys with ICPP recorded in the Portuguese national registry over the past 2 decades. Clinical, laboratory, and demographic characteristics of the patients were reviewed. Whole-exome sequencing (WES) was performed to identify pathogenic variants. Results: Of 736 children with CPP, 8.2% were males. Total CPP cases in boys increased significantly over time (p < 0.001), particularly during COVID-19. While secondary CPP remained stable (p = 0.198), idiopathic forms increased by 19.1%/year (p < 0.001), with change points in 2011 and 2021. WES identified pathogenic MKRN3 variants in 13.3% (2/15) boys, including a novel variant (p.Asp267Asn). MKRN3-positive patients presented with later-onset puberty, though sample size limits definitive conclusions. WES also detected a clinically significant TP53 variant as an incidental finding. Conclusion: ICPP incidence in Portuguese boys increased significantly over 2 decades, with acceleration during the pandemic. While genetic causes (primarily MKRN3 variants) were identified in 13.3% of cases, the substantial proportion of unexplained cases and temporal clustering indicate important roles for environmental and epigenetic factors.

CONTEXT:GH deficiency is a rare disorder characterized by severe short stature, which can result from genetic mutations affecting hypothalamic-pituitary development and function. OBJECTIVE:To determine the genetic basis of GH deficiency in a Portuguese cohort. DESIGN, SETTING, PATIENTS:Multicenter cohort of 203 GH-deficient patients (78 with isolated GH deficiency and 125 with combined pituitary hormone deficiency) were analyzed. INTERVENTION:Screening of a panel of 184 GH deficiency-related genes using Sanger sequencing and whole exome sequencing. MAIN OUTCOME MEASURE:Rare sequence variants (population maximum allele frequency <0.01). RESULTS:A genetic cause was identified in 23.2% of patients (9.0% in isolated GH deficiency and 32.0% in combined pituitary hormone deficiency). Mutations were found in the PROP1 (14.8% of patients), GLI2 (2.0%), KMT2D (1.0%), PROK2 (1.0%), PROKR2 (1.0%), CDON (0.5%), COL1A2 (0.5%), COL2A1 (0.5%), GHRHR (0.5%), PTPN11 (0.5%), and SOX3 (0.5%) genes. One patient (0.5%) had a digenic mutation in the BMP4 and NF1 genes. Variants of uncertain significance were identified in 87.8% of patients. CONCLUSION:This study revealed several novel and recurrent mutations that expand the genetic spectrum of GH deficiency and underscore the genetic heterogeneity of this disorder. A significant proportion of patients remained genetically undiagnosed, suggesting the involvement of additional unknown genetic, epigenetic, or environmental factors. These findings contribute to the understanding of the genetic architecture of GH deficiency and highlight the need for further investigations to elucidate underlying mechanisms and identify additional causative factors.

BackgroundIn histologically atypical congenital hyperinsulinism (CHI), correlations between clinical, histological and genetic features are largely unknown. Laser-capture microdissection may be used to identify low-grade mosaic DNA variants in the islets of Langerhans.AimTo investigate genotype-histotype-phenotype correlations histologically in atypical CHI.MethodsIn our single-center cohort of hyperinsulinemic hypoglycemia (HH) patients, 77 underwent pancreatic surgery. In those with histologically atypical CHI, genetic analyses included sequencing of frequent CHI genes from blood and bulk pancreatic tissue and tests for Beckwith-Wiedemann Syndrome (BWS) where appropriate. If negative, a targeted 140-gene panel including the non-coding region of HK1 was performed in blood, pancreatic bulk tissue and islets isolated by laser-capture microdissection. Histological, immunohistochemical and morphometric analyses were performed on pancreatic tissue.ResultsThe 77 HH patients were classified histologically as KATP-channel focal CHI (n=48), KATP-channel diffuse CHI (n=14), insulinoma (n=6), non-insulinoma HH in teenagers (n=1), BWS (n=1), unclassified (n=2). Histologically atypical CHI patients (n=5/70; 7.1%) had a median (range) birth weight of 2965 (2650-3385) grams and a clinical disease onset at 93 (1-259) days. 18F-DOPA PET/CT showed diffuse tracer uptake. In three patients, genetic analysis showed HK1 intron 2 variants, of which one was present in germline (de novo heterozygous) while the other two had somatic low-grade mosaic alterations in bulk pancreatic tissue (n=1) or exclusively in islets after isolation by laser-capture microdissection (n=1). Patient 4 showed a CACNA1D frameshift mutation suggesting Cav1.3-channel gain-of-function properties. No relevant genetic changes were found in Patient 5. In all five atypical CHI specimens, pancreatic histology showed slight changes with areas having pronounced occurrence of large islets of Langerhans, while small islets and endocrine cell clusters were evenly distributed. Giant cell nuclei were observed, but at much lower frequencies compared to KATP-channel diffuse CHI.ConclusionHistologically atypical CHI was seen in 7.1% of surgically treated CHI patients and characterized by discrete changes with enlarged islets of Langerhans and a low frequency of giant nuclei in endocrine cells. Genetics showed heterozygous or low-grade mosaic HK1 intron 2 DNA variants in three patients. Low-grade mosaic pancreatic genetic changes may only be detectable after islet isolation by laser-capture microdissection.

Background/Objectives: Hypoglycemia occurs when blood glucose levels drop significantly below the normal range leading to unpleasant symptoms and a greater risk of acute complications. Fear of hypoglycemia (FH) is a conditioned psychological response to hypoglycemia frequently experienced by people with type 1 diabetes (T1D) and their loved ones. The present study aimed to examine the psychometric properties of a Portuguese translation of the Hypoglycemia Fear Survey—Parents (HFS-P) for the parents of youths with T1D. Methods: The sample consisted of 102 parents (M = 44.58 years old; SD = 5.01; mothers = 92.2%) of youths with T1D (8 to 17 years of age; M = 12.67; SD = 2.58). Confirmatory Factor Analysis (CFA) and convergent validity were performed to examine the factor structure and the construct validity of the HFS-P. Results: CFA supports a refined two-factor 18-item version of the HFS-P. The results indicate good psychometric properties (χ2 [129] = 220.47.; p ≤ 0.001; χ2/DF = 1.71; RMSEA = 0.08; SRMR = 0.07; CFI = 0.93; TLI = 0.91; GFI = 0.93) along with good to excellent internal consistency coefficients (behavior subscale: α = 0.81, total: α = 0.93, and worry: α = 0.94). Conclusions: Our Portuguese version of the HFS-P appears reliable for assessing FH in parents of youths with T1D, and is ready for use in clinical research and to evaluate psychological interventions targeting parental FH in the Portuguese context.

Central precocious puberty (CPP) diagnosis often requires invasive GnRH stimulation tests. Our purpose was to determine whether the IGF-1 and IGF-1 SDSs are reliable predictors of progressive CPP. This was a prospective study including 82 girls under 8 years of age. The participants were divided into CPP (n = 39), NP-CPP and IT (n = 26), and control groups (n = 17). Anthropometric measurements, Tanner staging, bone age, pelvic ultrasound, and serum IGF1 and IGF1-SDS level measurements were performed. GnRH stimulation tests confirmed CPP cases. The mean IGF1 and IGF1-SDS levels were significantly greater in CPP patients (270.15 ng/mL; 1.943 SDS) than in NP-CPP patients (174.12 ng/mL; 0.788 SDS) and controls (139.28 ng/mL; 0.208 SDS) (p < 0.001). Multivariate logistic regression analysis confirmed that IGF1 (OR = 1.025, 95

Importance:Advanced diabetes technologies such as continuous glucose monitoring (CGM), continuous subcutaneous insulin infusion (insulin pumps [CSII]), and glucometers alongside insulin access represent the criterion standard for managing type 1 diabetes (T1D) in children. Global disparities in their access and reimbursement may be associated with glycemic outcomes. Objective:To describe how accessibility and reimbursement of advanced diabetes technologies and insulin are associated with glycated hemoglobin (HbA1c) levels in centers participating in the SWEET initiative, an international pediatric diabetes registry. Design, Setting, and Participants:This global multicenter cross-sectional study collected data from 81 centers in 56 countries. Web-based questionnaires were distributed to representatives of all 121 pediatric diabetes centers participating in the SWEET initiative from March 1 to May 31, 2024, and used to map accessibility of and reimbursement for CGM, CSII, glucometers, and insulin. Reimbursement data were compared with HbA1c levels using the SWEET Study dataset. Participants included 42 349 children with T1D. Exposures:Responses were categorized into 4 groups based on the extent of reimbursement for diabetes technologies and insulin. Main Outcomes and Measures:Mean HbA1c levels across centers calculated from measurements current as of December 31, 2023, analyzed by categories of accessibility of and reimbursement for diabetes technologies and insulin. Results:Data collected from 81 of 121 SWEET centers (67%) across 56 countries included HbA1c levels from 42 349 children with T1D (22 021 male [52%]; mean [SD] age, 14.3 [4.4] years; mean [SD] diabetes duration, 6.0 [4.2] years). Universal access with complete reimbursement for all technologies and insulin was reported by 32 centers from 19 countries, while 8 countries reported no reimbursement for any technologies or insulin. Centers with full reimbursement for CSII, CGM, glucometers, and insulin showed mean HbA1c levels of 7.62% (95% CI, 7.59%-7.64%) to 7.75% (95% CI, 7.73%-7.77%) compared with 9.65% (95% CI, 9.55%-9.71%) to 10.49% (95% CI, 10.40%-10.58%) in centers with no reimbursement and/or no availability (P < .001 for all items). Conclusions and Relevance:This cross-sectional study found that HbA1c levels were associated with the accessibility of modern diabetes technologies and insulin. Efforts to ensure universal accessibility are required to reduce global inequities and glycemic outcomes for children with T1D.

Aims: This study is aimed at comparing whole exome sequencing (WES) data with the clinical presentation in children with type 1 diabetes onset ≤ 5 years of age (EOT1D). Methods: WES was performed in 99 unrelated children with EOT1D with subsequent analysis to identify potentially deleterious rare variants in MODY genes. High-resolution HLA class II haplotyping, SNP genotyping, and T1D-genetic risk score (T1D-GRS) were also evaluated. Results: Eight of the ninety-nine EOT1D participants carried a potentially deleterious rare variant in a MODY gene. Rare variants affected five genes: GCK (n = 1), HNF1B (n = 2), HNF4A (n = 1), PDX1 (n = 2), and RFX6 (n = 2). At diagnosis, these children had a mean age of 3.0 years, a mean HbA1c of 10.5%, a detectable C-peptide in 5/8, and a positive islet autoantibody in 6/7. Children with MODY variants tend to exhibit a lower number of pancreatic autoantibodies and a lower fasting C-peptide compared to EOT1D without MODY rare variants. They also carried at least one high-risk DR3-DQ2 or DR4-DQ8 haplotype and exhibited a T1D-GRS similar to the other individuals in the EOT1D cohort, but higher than healthy controls. Conclusions: WES found potentially deleterious rare variants in MODY genes in 8.1% of EOT1D, occurring in the context of a T1D genetic background. Such genetic variants may contribute to disease precipitation by a β-cell dysfunction mechanism. This supports the concept of different endotypes of T1D, and WES at T1D onset may be a prerequisite for the implementation of precision therapies in children with autoimmune diabetes.

Introduction:Early-onset Type 1 diabetes (EOT1D) is considered a disease subtype with distinctive immunological and clinical features. While both Human Leukocyte Antigen (HLA) and non-HLA variants contribute to age at T1D diagnosis, detailed analyses of EOT1D-specific genetic determinants are still lacking. This study scrutinized the involvement of the HLA class II locus in EOT1D genetic control.Methods:We conducted genetic association and regularized logistic regression analyses to evaluate genotypic, haplotypic and allelic variants in DRB1, DQA1 and DQB1 genes in children with EOT1D (diagnosed at ≤5 years of age; n=97), individuals with later-onset disease (LaOT1D; diagnosed 8-30 years of age; n=96) and nondiabetic control subjects (n=169), in the Portuguese population.Results:Allelic association analysis of EOT1D and LaOT1D unrelated patients in comparison with controls, revealed that the rare DRB1*04:08 allele is a distinctive EOT1D susceptibility factor (corrected p-value=7.0x10-7). Conversely, the classical T1D risk allele DRB1*04:05 was absent in EOT1D children while was associated with LaOT1D (corrected p-value=1.4x10-2). In corroboration, HLA class II haplotype analysis showed that the rare DRB1*04:08-DQ8 haplotype is specifically associated with EOT1D (corrected p-value=1.4x10-5) and represents the major HLA class II genetic driver and discriminative factor in the development of early onset disease.Discussion:This study uncovered that EOT1D holds a distinctive spectrum of HLA class II susceptibility loci, which includes risk factors overlapping with LaOT1D and discriminative genetic configurations. These findings warrant replication studies in larger multicentric settings encompassing other ethnicities and may impact target screening strategies and follow-up of young children with high T1D genetic risk as well as personalized therapeutic approaches.

Background Early-onset Type 1 diabetes (EOT1D) is considered a disease subtype with distinctive immunological and clinical features. While both Human Leukocyte Antigen (HLA) and non-HLA variants contribute to age at T1D diagnosis, detailed analyses of EOT1D-specific genetic determinants are still lacking. This study scrutinized the involvement of the HLA class II locus in EOT1D genetic control.Methods We conducted genetic association and regularized logistic regression analyses to evaluate genotypic, haplotypic and allelic variants in DRB1 , DQA1 and DQB1 genes in children with EOT1D (diagnosed at ≤5 years of age; n=97), individuals with later-onset disease (LaOT1D; diagnosed 8-30 years of age; n=96) and nondiabetic control subjects (n=169), in the Portuguese population.Findings Analysis of EOT1D and LaOT1D unrelated patients in comparison with controls, revealed the rare DRB1*04:08-DQ8 haplotype is specifically associated with EOT1D (corrected p-value=1.4×10-5) and represents the major discriminative HLA class II genetic factor. Allelic association further indicated the DRB1*04:08 allele is a distinctive EOT1D susceptibility factor (corrected p-value=7.0×10-7). Conversely, the classical T1D risk allele DRB1*04:05 was absent in EOT1D children while was associated with LaOT1D (corrected p-value=1.4×10-2).Interpretation This study uncovered that EOT1D holds a distinctive spectrum of HLA class II susceptibility loci , which includes risk factors overlapping with LaOT1D and discriminative genetic configurations. These findings warrant replication studies in larger multicentric settings and may impact target screening strategies and follow-up of young children with high T1D genetic risk.Funding European Foundation for the Study of Diabetes, Maratona da Saúde and Fundação para a Ciência e a Tecnologia.### Competing Interest StatementThe authors have declared no competing interest.### Funding StatementThis work was supported by the European Foundation for the Study of Diabetes (EFSD/JDRF/Lilly Programme 2016), Maratona da Saúde and Fundaçāo para a Ciência e a Tecnologia (CEECIND/00148/2017 to Iris Caramalho).### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:Ethical permissions for this study were obtained from the Ethics Committee from Hospital de Dona Estefênia (HDE; Comissāo de Ética para a Saúde, Centro Hospital de Lisboa Central, #318/2016), and the Ethics Committee from Associaçāo Protetora dos Diabéticos de Portugal (APDP).I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.YesAll data produced in the present study are available upon reasonable request to the authors.

Unit of Paediatric Endocrinology and Diabetes, Hospital Dona Estefânia, Lisbon, Portugal Nova Medical School, Universidade Nova de Lisboa, Lisbon, Portugal Department of Pediatrics, University of Turin, Turin, Italy Department of Pediatrics, University of Washington, Seattle, Washington, USA Department of Endocrinology, Growth & Development, “P&A Kyriakou” Children's Hospital, Athens, Greece Barbara Davis Center, University of Colorado School of Medicine, Aurora, Colorado, USA Pusat Perubatan, Universiti Malaya, Kuala Lumpur, Malaysia Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Sydney, New South Wales, Australia Discipline of Paediatrics and Child Health, University of Sydney, Sydney, New South Wales, Australia Diabetes-Center for Children and Adolescents, Children's Hospital "Auf der Bult", Hannover, Germany Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA Division of Pediatric Endocrinology and Diabetology, Campus Lübeck, University Medical Centre Schleswig-Holstein, Lübeck, Germany Department of Paediatrics, University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK

Introduction: Our aim was to characterize new-onset type 1 diabetes mellitus (T1D) cases in a pediatric population referred to a large pediatric diabetic center throughout the first year of the COVID-19 pandemic, comparing it to previous years. Methods: Retrospective study including patients under 18 years with new-onset T1D, from March 12th 2020 to March 11(th) 2021. A control group was defined using data on patients under 18 years with new-onset T1D referred to the same hospital in the 3 previous years (from March 2017 to March 2020). Data was analyzed using SPSS. A p value of 0.05 was used as threshold of significance. Results: Between March 12(th) 2020 and March 12(th) 2021, 44 patients were diagnosed with new-onset T1D. The control group included 96 patients, resulting in an incidence of 32 cases/year (37.5% rise). January 2021 was the month with the higher number of diagnosis, corresponding to the peak of novel SARS-CoV-2 infections. During the pandemic, new-onset T1D cases in children under 2 years-old doubled, when comparing to mean incidence in previous years. Median delay to diagnosis was not significantly different from previous years. Diabetic ketoacidosis (DKA) at presentation was present in 50% of cases that were diagnosed after lockdown, increasing substantially from previous years (38.5%). DKA's severity was also significantly higher (40.9%, p=0.04), as were Intensive Care Unit admission (13.6%, p=0.04). Conclusion: Despite the existance of molecular pathways that could lead to islet cell injury, the role of the new coronavirus in the pathogenesis of DKA and T1D onset is still unclear. Disease severity could also be related to a higher proportion of younger children.