Beckwith-Wiedemann Research Articles

Non-malignant features of cancer predisposition syndromes manifesting in childhood and adolescence: a guide for the general pediatrician.

Cancer predisposition syndromes are genetic disorders that significantly raise the risk of developing malignancies. Although the malignant manifestations of cancer predisposition syndromes are well-studied, recognizing their non-malignant features is crucial for early diagnosis, especially in children and adolescents. A comprehensive literature search was conducted using the PubMed database, focusing on non-malignant manifestations of cancer predisposition syndromes in children and adolescents. Key sources included the Clinical Cancer Research pediatric oncology series and ORPHANET. Studies that described clinical signs and symptoms affecting specific organ systems were included. Non-malignant dermatological features often serve as early indicators of cancer predisposition syndromes, including café-au-lait spots in Neurofibromatosis Type 1 and facial angiofibromas in Tuberous Sclerosis Complex. Neurological and developmental anomalies such as cerebellar ataxia in ataxia-telangiectasia and intellectual disabilities in neurofibromatosis type 1 and tuberous sclerosis complex are significant indicators. Growth and metabolic anomalies are also notable, including overgrowth in Beckwith-Wiedemann syndrome and growth hormone deficiency in neurofibromatosis Type 1. In addition, facial anomalies, ocular manifestations, hearing issues, and thyroid anomalies are prevalent across various cancer predisposition syndromes. For instance, hearing loss may be significant in neurofibromatosis Type 2, while thyroid nodules are common in PTEN hamartoma tumor syndrome and DICER1 syndrome. Cardiovascular, abdominal, musculoskeletal, pulmonary, genitourinary manifestations, and prenatal deviations further complicate the clinical picture. Recognizing non-malignant features of cancer predisposition syndromes is essential for early diagnosis and management. This organ-specific overview furthers awareness among healthcare providers, facilitating timely genetic counseling, surveillance programs, and preventive measures, ultimately improving patient outcomes.

Role of Nasopharyngeal Airway in Management of Craniofacial Syndrome-Associated Upper Airway Obstruction in Children.

Upper airway obstruction (UAO) management in children, particularly those with associated anatomical mid-face structural differences, poses a significant challenge. This study describes using a nasopharyngeal airway (NPA) in managing infants with severe upper airway obstruction. Infants discharged home from Queensland Children's Hospital with an NPA insitu for the management of upper airway obstruction were retrospectively evaluated for clinical and demographic parameters, underlying diagnoses and respiratory support, including NPA insertion details and comorbidities. Sixty-seven children (24 male) were included with a median age at NPA insertion of 24 (IQR 7-59) days and a median duration of NPA use of 229.1 (IQR 151.50-297.75) days. Fifty-two (77.6%) had Pierre Robin sequence. Other diagnoses included CHARGE syndrome, Treacher Collins syndrome, Stickler syndrome, Crouzon syndrome, Bohring-Opitz syndrome, isolated cleft palate, Beckwith-Wiedemann syndrome, Chromosome 3 deletion and VACTERL association. Four infants required tracheostomy, and no complications related to NPA use were reported. Those with oximetry and polysomnography data showed improving indices following NPA insertion [pre NPA median (IQR) SpO2: 95.9% (94.73-97.73), AHI: 51.40 (44.50-69.45), OAHI 65.9 (56.45-73.35) and TcCO2 (mmHg) 65.70 (61.95-67.30) vs. post-NPA median (IQR) SpO2: 97.1% (96.19-97.9), AHI: 12.20 (11.25-24.35), OAHI 10.20 (6.12-5.62) and TcCO2 (mmHg) 52.40 (47.90-58.40)]. Our findings highlight the effectiveness and safety of NPA as a noninvasive management option for severe upper airway obstruction in children, particularly in those with anatomical midface structural differences. Further research and larger studies are warranted to confirm these findings and optimise management strategies for these patients.

Genome-wide screening reveals essential roles for HOX genes and imprinted genes during caudal neurogenesis of human embryonic stem cells

Mapping the essential pathways for neuronal differentiation can uncover new therapeutics and models for neurodevelopmental disorders. We thus utilized a genome-wide loss-of-function library in haploid human embryonic stem cells, differentiated into caudal neuronal cells. We show that essential genes for caudal neurogenesis are enriched for secreted and membrane proteins and that a large group of neurological conditions, including neurodegenerative disorders, manifest early neuronal phenotypes. Furthermore, essential transcription factors are enriched with homeobox (HOX) genes demonstrating synergistic regulation and surprising non-redundant functions between HOXA6 and HOXB6 paralogs. Moreover, we establish the essentialome of imprinted genes during neurogenesis, demonstrating that maternally expressed genes are non-essential in pluripotent cells and their differentiated germ layers, yet several are essential for neuronal development. These include Beckwith-Wiedemann syndrome- and Angelman syndrome-related genes, for which we suggest a novel regulatory pathway. Overall, our work identifies essential pathways for caudal neuronal differentiation and stage-specific phenotypes of neurological disorders.

Isolated Lateralized Overgrowth - Phenotypic Spectrum and Molecular Alterations.

To evaluate the molecular aberrations at 11p15.5 locus in thirty-two patients with isolated lateralized overgrowth (ILO). Among selected 32 cases of ILO, methylation-sensitive multiplex ligation-dependent probe amplification (MS-MLPA) was performed initially followed by short tandem repeats (STR) marker analysis to confirm uniparental disomy (UPD). In those patients with normal MLPA reports, cyclin dependent kinase inhibitor 1C (CDKN1C) gene and whole exome sequencing was performed. Molecular analysis by MS-MLPA showed methylation aberrations in 28% (9/32) of patients. Gain of methylation at IC1 imprinting center (H4, H7) and loss of methylation at IC2 (H6, H9) was observed in 2 patients each. Uniparental disomy was observed in 9% cases. Except one, all patients with methylation aberration had more than one limb hypertrophy. Two patients (H22/H29) also had loss of methylation at IC1. Though this molecular alteration is specifically associated with Silver Russel syndrome (SRS), but the affected children did not completely fulfill the diagnostic criteria for SRS. In a recent study, a discrepancy was reported between the diagnosis of Beckwith-Wiedemann syndrome (BWS)/SRS and the molecular findings in the patients. Many times, it is very difficult to differentiate between hemi hypertrophy/hemi hypotrophy. Patients, in whom no aberrations were detected on MS-MLPA, whole exome sequencing (WES) was performed and no pathogenic variant was identified. Thus, ILO may be considered as a mild presentation on the extreme edge of BWS spectrum with methylation aberration and UPDin one thirdof cases which has implications in follow up.

Morphometric measurements of intraoral anatomy in children with Beckwith-Wiedemann syndrome: a novel approach

BackgroundAn easy-to-use tool to objectively measure intraoral anatomy with meaningful clinical correlations may improve care for patients with Beckwith-Wiedemann syndrome (BWS), who commonly have symptomatic macroglossia.MethodsChildren aged 2–17 years with BWS were enrolled between 12/2021 and 01/2024. Digital intraoral photographs with a laser ruler were taken, and morphometric measurements were made using ImageJ software. Relationships between morphometrics and outcomes including BWS clinical score, percentage mosaicism, and incidence of tongue reduction surgery were examined using t-tests and multivariate linear models.ResultsPharyngeal morphometric measurements were obtained in 49 patients with BWS. Mouth area, width, and height differed significantly across BWS molecular subtypes. Right-to-left tongue width and mouth width were larger in those with loss of methylation at imprinting control region 2 (IC2 LOM) than other BWS variants. Patients with paternal uniparental isodisomy of chromosome 11p15 (pUPD11) had narrower mouths than others. Those with tongue reduction surgery had more tongue ridging than those without surgery. There were correlations between mouth area and BWS clinical score, tongue width and BWS clinical score, and tongue length and percentage mosaicism.ConclusionIntraoral morphometric measurements are associated with phenotypic burden in BWS. Tongue morphology varies across the BWS spectrum, with IC2 LOM having wider tongues and mouths, and pUPD11 having narrower mouths. Tongue ridging is more common in those selected for surgery. Intraoral morphometric measurements may be safely obtained at low costs across centers caring for children with BWS or others at risk of upper airway obstruction.

Update on surveillance for Wilms tumor and hepatoblastoma in Beckwith-Wiedemann Syndrome and other predisposition syndromes.

Wilms tumors are commonly associated with predisposition syndromes many, but not all, of which include overgrowth. Several of these syndromes also include a risk of other embryonal malignancies - particularly hepatoblastoma. Guidelines for surveillance in this population were published in 2017 and recently members of the AACR Pediatric Cancer Working Group met to update those guidelines with a review of more recently published evidence and risk estimates. This perspective serves to update pediatric oncologists, geneticists, radiologists, counselors and other healthcare professionals on revised diagnostic criteria, review previously published surveillance guidelines and harmonize updated surveillance recommendations in the North American and Australian context for patients with overgrowth syndromes and other syndromes associated with Wilms tumor predisposition.

Hiding in Plain Sight: Radiologic and Pathologic Findings Can Identify Beckwith-Wiedemann Syndrome in Patients With Wilms Tumor.

Most pediatric specialists, including hematologists/oncologists, surgeons, radiologists, and pathologists, are familiar with the diagnosis and management of Wilms tumor (WT). However, it may be challenging to identify the underlying conditions causing cancer predisposition, which can change the management for the patient and potentially their entire family. In this paper, we present 3 cases of clinically suspected WT associated with Beckwith-Wiedemann syndrome (BWS). We review the radiologic and histologic findings to diagnose BWS. We also discuss the implications of a BWS diagnosis on the clinical management of WT and follow-up guidelines for BWS patients.

The molecular genetics of adrenal cushing.

Adrenal Cushing represents 20% of cases of endogenous hypercorticism. Unilateral cortisol-producing adenoma (CPA), a benign tumor, and adrenocortical carcinoma (ACC), a malignant tumor, are more frequent than bilateral adrenal nodular diseases (primary bilateral macronodular adrenal hyperplasia (PBMAH) and primary pigmented nodular adrenal disease (PPNAD)).In cortisol-producing adrenal tumors, the signaling pathways mainly altered are the protein kinase A and Wnt/β-catenin pathways. Studying components of these pathways and exploring syndromic and familial cases of these tumors has historically enabled identification of many of the predisposing genes. More recently, pangenomic sequencing revealed alterations in sporadic tumors.In ACC, mainly due to TP53 alterations causing Li-Fraumeni syndrome, germline predisposition is frequent in children, while it is rare in adults. Pathogenic variants in the DNA mismatch repair genes MLH1, MSH2, MSH6, and PMS2, which cause Lynch syndrome or alterations of IGF2 and CDKN1C (11p15 locus) in Beckwith-Wiedemann syndrome, can also cause ACC. Rarely, ACC is described in other hereditary tumor syndromes due to germline pathogenic variants in MEN1 or APC and, in very rare cases, NF1, SDH, PRKAR1A, or BRCA2. Concerning ACC somatic alterations, TP53 and genetic or epigenetic alterations at the 11p15 locus are also frequently described, as well as CTNNB1 and ZNRF3 pathogenic variants.CPAs mainly harbor somatic pathogenic variants in PRKACA and CTNNB1 and, less frequently, PRKAR1A, PRKACB, or GNAS1 pathogenic variants. Isolated PBMAH is due to ARMC5 inactivating pathogenic variants in 20 to 25% of cases and to KDM1A pathogenic variants in food-dependent Cushing. Syndromic PBMAH may be due to germline pathogenic variants in MEN1, APC, or FH, causing type 1 multiple endocrine neoplasia, familial adenomatous polyposis, or hereditary leiomyomatosis-kidney cancer syndrome, respectively. PRKAR1A germline pathogenic variants are the main alteration causing PPNAD (isolated or part of Carney complex).

6775 Four Cases with the Beckwith-Wiedemann Syndrome Phenotype Caused by GNAS Defects

Abstract Disclosure: T. Urakawa: None. Y. Kanamaru: None. N. Amano: None. A. Uchida: None. J. Shin: None. M. Fukami: None. M. Kagami: None. Background: Beckwith-Wiedemann syndrome (BWS) is an overgrowth disorder with a heterogeneous phenotypic spectrum, including macroglossia (MG), lateralized overgrowth (LO), and hyperinsulinism (HI). According to the BWS clinical scoring system, the consensus statement recommends conducting genetic testing for patients with two or more scores and doing the clinical diagnosis of BWS for patients with four or more scores. The etiologies of BWS consist of methylation abnormalities of differentially methylated regions (DMRs) on 11p15.5, paternal uniparental disomy of chromosome 11 (UPD(11)pat), and maternal loss of function variants of CDKN1C. However, in 20% of BWS cases, the genetic causes remain unclear. Here, we report on four cases of the BWS phenotype with GNAS defects, known to cause pseudohypoparathyroidism (PHP). Case presentation: Case 1 was born at 37 weeks of gestation with birth weight (BW) of 2964 g (+0.8 SD) and birth length (BL) of 50.5 cm (+1.3 SD) and had MG, LO, HI, ear creases (EC), naevus flammeus, umbilical hernia (UH), and postnatal overgrowth (PO) together with intellectual disability (BWS score 9). Case 2 was born at 32 weeks with BW of 1415 g (-1.4 SD) and BL of 40.0 cm (-0.8 SD), showing MG, HI, UH, and PO (BWS score 5). Case 3 was born at 36 weeks with BW of 2366 g (-0.5 SD) and BL of 44.0 cm (-1.1 SD), exhibiting MG, EC, UH, and PO (BWS score 4). Case 4 was born at 36 weeks with BW of 2762 g (+0.6 SD) and BL of 46.0 cm (-0.4 SD), presenting MG and PO (BWS score 2). Cases 3 and 4 showed elevated intact PTH levels. Genetic analysis: Methylation-specific MLPA (MS-MLPA) for multiple DMRs showed abnormal methylation in DMRs on the GNAS locus in cases 1-3, but normal methylation levels in DMRs on 11p15.5. Case 1 had multi-locus imprinting disturbance (MLID) detected by comprehensive methylation analysis (EPIC, Illumina) and a 9pter-9p24.2 deletion identified by array CGH analysis. Case 2 also had MLID together with UPD(20)pat detected by microsatellite marker analysis. Case 3 showed only abnormal methylation in the DMRs on the GNAS locus confirmed by a comprehensive methylation analysis. Case 4 showed no abnormal methylation in the DMRs examined by MS-MLPA and had a pathogenic variant in GNAS (F219L) detected by exome sequencing. Discussion: We identified GNAS defects in four cases with the BWS phenotype. MG and PO were observed in all cases, and other BWS features in each case. Some clinical features observed in 9p terminal deletion syndrome and PHP overlap those in BWS, such as HI, MG, and PO. Therefore, these diseases should be considered as the differential diagnosis of BWS. MLID was identified in two cases, but the methylation status of DMRs on 11p15.5 was normal. The impact of MLID on the BWS phenotype is unknown. Conclusion:GNAS defects can cause the BWS phenotype. Further genetic analysis including GNAS should be considered in cases with the BWS phenotype without 11p15.5 abnormalities. Presentation: 6/2/2024

Comprehensive molecular and clinical findings in 29 patients with multi-locus imprinting disturbance

BackgroundMulti-locus imprinting disturbance (MLID) with methylation defects in various differentially methylated regions (DMRs) has recently been identified in approximately 150 cases with imprinting disorders (IDs), and deleterious variants have been found in genes related to methylation maintenance of DMRs, such as those encoding proteins constructing the subcortical maternal complex (SCMC), in a small fraction of patients and/or their mothers. However, integrated methylation analysis for DMRs and sequence analysis for MLID-causative genes in MLID cases and their mothers have been performed only in a single study focusing on Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) phenotypes.ResultsOf 783 patients with various IDs we have identified to date, we examined a total of 386 patients with confirmed epimutation and 71 patients with epimutation or uniparental disomy. Consequently, we identified MLID in 29 patients with epimutation confirmed by methylation analysis for multiple ID-associated DMRs using pyrosequencing and/or methylation-specific multiple ligation-dependent probe amplification. MLID was detected in approximately 12% of patients with BWS phenotype and approximately 5% of patients with SRS phenotype, but not in patients with Kagami-Ogata syndrome, Prader-Willi syndrome, or Angelman syndrome phenotypes. We next conducted array-based methylation analysis for 78 DMRs and whole-exome sequencing in the 29 patients, revealing hypomethylation-dominant aberrant methylation patterns in various DMRs of all the patients, eight probably deleterious variants in genes for SCMC in the mothers of patients, and one homozygous deleterious variant in ZNF445 in one patient. These variants did not show gene-specific methylation disturbance patterns. Clinically, neurodevelopmental delay and/or intellectual developmental disorder (ND/IDD) was observed in about half of the MLID patients, with no association with the identified methylation disturbance patterns and genetic variants. Notably, seven patients with BWS phenotype were conceived by assisted reproductive technology (ART).ConclusionsThe frequency of MLID was 7.5% (29/386) in IDs caused by confirmed epimutation. Furthermore, we revealed diverse patterns of hypomethylation-dominant methylation defects, nine deleterious variants, ND/IDD complications in about half of the MLID patients, and a high frequency of MLID in ART-conceived patients.

Cognitive, Social, and Emotional-Behavioral Outcomes in Children and Adolescents With Beckwith-Wiedemann Syndrome.

Although Beckwith-Wiedemann syndrome spectrum (BWSp) is not usually associated with intellectual disability, recent evidences calls for further investigation of cognitive development and academic skills in children with BWSp. Moreover, research has documented social difficulties and emotional-behavioral problems associated with BWSp. Nevertheless, a full characterization of socio-emotional development in BWSp is still lacking. In the current study, cognitive and socio-emotional development was assessed in 29 children with BWSp aged 5-18 years, using a test of nonverbal intelligence, a neuropsychological battery covering multiple domains, academic skills tests, and questionnaires evaluating autistic traits and emotional-behavioral problems. As expected, most participants showed adequate performance in cognitive tests. However, the findings also highlighted greater difficulties in language than visuospatial processing, strengths in social perception, as well as slowness in reading and mental calculation. The assessment of emotional-behavioral difficulties indicated a prevalent phenotype characterized by increased anxiety, low self-esteem, social withdrawal and a tendency to control externalizing reactions, but no associations with autistic traits, cognitive outcomes, and the clinical score proposed by the recent Consensus statement. Increased social perception and internalization problems likely result from coping strategies with social and care-related stress. Overall, the findings of this study inform clinical management and genetic counseling for children and adolescents with BWSp.

Management strategies and patient outcomes of congenital hyperinsulinism (CHI) related with beckwith-wiedemann syndrome (BWS) - insights from an CHI highly specialized centre

Management strategies and patient outcomes of congenital hyperinsulinism (CHI) related with beckwith-wiedemann syndrome (BWS) - insights from an CHI highly specialized centre

The Peripheral Reduction With Keyhole Tongue Reduction Technique for Macroglossia in Beckwith-Wiedemann Syndrome.

Patients with Beckwith-Wiedemann syndrome commonly have macroglossia, which can negatively affect dentoskeletal development, breathing, speaking, and eating. Tongue reduction surgery can improve symptoms, but there is no standardized surgical approach. A video and observational commentary highlighting the effectiveness of a tongue reduction technique for BWS were presented. The peripheral resection with a keyhole approach safely reduced tongue volume, maintained the lateral neurovascular pedicles, optimized intraoperative visualization, and limited bleeding. The peripheral resection with a keyhole tongue reduction surgical technique is effective for treating symptomatic macroglossia in BWS.

NanoImprint: A DNA methylation tool for clinical interpretation and diagnosis of common imprinting disordersusing nanopore long-read sequencing.

Long-read whole genome sequencing like Oxford Nanopore Technology, is increasingly being introduced in clinical settings. With its ability to simultaneously call sequence variation and DNA modifications including 5-methylcytosine, nanopore is a promising technology to improve diagnostics of imprinting disorders. Currently, no tools to analyze DNA methylation patterns at known clinically relevant imprinted regions are available. Here we present NanoImprint, which generates an easily interpretable report, based on long-read nanopore sequencing, to use for identifying clinical relevant abnormalities in methylation levels at 14 imprinted regions and diagnosis of common imprinting disorders. NanoImprint outputs a summarizing table and visualization plots displays methylation frequency (%) and chromosomal positions for all regions, with phased data color-coded for the two alleles. We demonstrate the utility of NanoImprint using three imprinting disorder samples from patients with Beckwith-Wiedemann syndrome (BWS), Angelman syndrome (AS) and Prader-Willi syndrome (PWS). NanoImprint script is available from https://github.com/carolinehey/NanoImprint.

The Fetus Points to the Diagnosis of Rare Skeletal Dysplasia: Stuve–wiedemann Syndrome: Retrospective Case Series and Prenatal Review

The Fetus Points to the Diagnosis of Rare Skeletal Dysplasia: Stuve–wiedemann Syndrome: Retrospective Case Series and Prenatal Review

O-210 DNA methylation signature of monozygotic twinning: investigating the relationship with medically assisted reproduction, higher-order gestations, and common genetic variants

Abstract Study question To study a DNA methylation signature of monozygotic twins in relation to medically assisted reproduction (MAR), higher-order gestations, and genome-wide common genetic variants. Summary answer Monozygotic twinning and MAR show largely distinct DNA methylation signatures. Monozygotic triplets, like monozygotic twins, carry a comparable but stronger DNA methylation signature. What is known already Monozygotic twins arise when a zygote or embryo splits during pre-implantation stages of development. Higher-order monozygotic multiples including triplets have been hypothesized to arise from multiple consecutive splitting events. The underlying mechanisms are unknown. Some studies have reported a higher rate of monozygotic twins born after the use of medically-assisted reproductive technologies. We recently identified a DNA methylation signature in blood samples from adult monozygotic twins, which showed strong replication across cohorts and in buccal samples from children. This signature consists of 834 differentially methylated locations, enriched for loci with a role in embryonic processes, cell adhesion, and metastable epi-alleles. Study design, size, duration We compared buccal DNA methylation profiles of 934 naturally conceived monozygotic twins to 43 monozygotic twins conceived after IVF/ICSI (mean age=9). We generated monozygotic twinning DNA methylation scores in an independent buccal dataset (59 triplets, 198 twins, and 119 siblings of twins, mean age=15). A genome-wide association study (GWAS) on the DNA methylation score was performed in two datasets from the Netherlands Twin Register (NTR) (1: Blood, N = 2841, mean age=37, 2: Buccal, N = 1150, mean age=10). Participants/materials, setting, methods DNA methylation was assessed with Illumina arrays (450k/EPIC). To study the relationship between DNA methylation and MAR, we performed an epigenome-wide association study (EWAS) of MAR in monozygotic twins. We applied our previously developed DNA-methylation based predictor (trained on blood methylation data from twins using elastic net regression) to novel buccal methylation data from multiples including triplets. GWAS analysis was performed in gcta using --fastGWA-mlm correcting for 10 genetic ancestry PCs and genotype platform. Main results and the role of chance Through EWAS, we identified 29 differentially methylated CpGs in buccal cells from monozygotic twins conceived after MAR compared to naturally conceived monozygotic twins (after Bonferroni correction), of which 8 were previously identified in an EWAS meta-analysis of IVF on cord blood from singletons at birth. None of the 834 CpGs detected in our previous EWAS meta-analysis of monozygotic twinning were associated with MAR, suggesting that they are connected to natural monozygotic twinning. The monozygotic twinning epigenetic signature showed similar performance in buccal DNA methylation data from monozygotic twins as previously observed (81% of monozygotic twins correctly classified). Sensitivity was highest for monozygotic triplets (90% correctly classified), but specificity remains moderate (66% of DZ twins correctly predicted, 53% of non-twins correctly predicted). GWAS analysis of blood 450k array data identified three genome-wide significant loci. The top SNP (rs76157694, MAF=0.25) maps to TBX4; an embryonic transcription factor primarily known for its role in hindlimb development. This finding is consistent with our previous results of MZ-differentially methylated positions being enriched within TBX4 binding motifs. GWAS analysis of the buccal EPIC array data identified no genome-wide significant loci. We are planning a GWAS meta-analysis together with the Genetics of DNA methylation consortium. Limitations, reasons for caution Our research provides compelling hints towards an epigenomic event in monozygotic multiples, but whether the signature represents a cause, effect, or a byproduct of monozygotic twinning remains to be established. In ongoing research, we study the signature in pre- and perinatal tissues from twins (Dutch Fetal biobank and PANDA biobank). Wider implications of the findings The methylation signature may serve as a biomarker to retrospectively diagnose if a person was conceived as monozygotic twin, providing novel opportunities to examine links between vanishing monozygotic twin syndrome and certain congenital disorders. Examples include Beckwith-Wiedemann Syndrome and Amyoplasia (∼10-fold higher frequency of monozygotic twins among patients). Trial registration number not applicable

Genotype-histotype-phenotype correlations in hyperinsulinemic hypoglycemia.

Hyperinsulinemic hypoglycemia (HH) of pancreatic origin includes congenital hyperinsulinism (CHI), insulinoma, insulinomatosis, and adult-onset non-insulinoma persistent hyperinsulinemic hypoglycemia syndrome (NI-PHHS). In this review, we describe the genotype-histotype-phenotype correlations in HH and their therapeutic implications. CHI can occur from birth or later on in life. Histologically, diffuse CHI shows diffuse beta cell hypertrophy with a few giant nuclei per islet of Langerhans, most frequently caused by loss-of-function mutations in ABCC8 or KCNJ11. Focal CHI is histologically characterized by focal adenomatous hyperplasia consisting of confluent hyperplastic islets, caused by a paternal ABCC8/KCNJ11 mutation combined with paternal uniparental disomy of 11p15. CHI in Beckwith-Wiedemann syndrome is caused by mosaic changes in the imprinting region 11p15.4-11p15.5, leading to segmental or diffuse overgrowth of endocrine tissue in the pancreas. Morphological mosaicism of pancreatic islets is characterized by occurence of hyperplastic (type 1) islets in one or a few lobules and small (type 2) islets in the entire pancreas. Other rare genetic causes of CHI show less characteristic or unspecific histology. HH with a predominant adult onset includes insulinomas, which are pancreatic insulin-producing endocrine neoplasms, in some cases with metastatic potential. Insulinomas occur sporadically or as part of multiple endocrine neoplasia type 1 due to MEN1 mutations. MAFA mutations may histologically lead to insulinomatosis with insulin-producing neuroendocrine microadenomas or neuroendocrine neoplasms. NI-PHHS is mainly seen in adults and shows slight histological changes in some patients, which have been defined as major and minor criteria. The genetic cause is unknown in most cases. The diagnosis of HH, as defined by genetic, histological, and phenotypic features, has important implications for patient management and outcome.

Prenatal Diagnosis of Beckwith-Wiedemann Syndrome with Omphalocele.

Prenatal Diagnosis of Beckwith-Wiedemann Syndrome with Omphalocele.

Successful noninvasive ventilation in a child with Beckwith-Wiedemann syndrome and obstructive sleep apnea.

Successful noninvasive ventilation in a child with Beckwith-Wiedemann syndrome and obstructive sleep apnea.

METB-02. GENETIC COUNSELLING IN SOTOS AND NS1-RELATED OVERGROWTH SYNDROMES PREDISPOSING TO BRAIN TUMORS

Abstract BACKGROUND Sotos and many other overgrowth syndromes are among the rare tumor predisposition syndromes that might be under-recognized in pediatric neuro-oncology practice. NSD1 gene (5q35), belonging to the histone lysine methyltransferases family, is involved in the majority of Sotos patients who exhibited haploinsufficiency and loss-of-function variants of the gene, but also in other overgrowth entities such as Beckwith-Wiedemann syndrome. Somatic mutations in this gene are likewise responsible of numerous cancers, particularly brain tumors. Here, we aim to assess the neurologic cancer risks and provide genetic counseling for appropriate clinical follow-up in Sotos syndrome. METHODS From our genetic counseling database at the medical University of Sfax (Tunisia), we selected among patients presented for genetic management of overgrowth syndromes, those with Sotos syndrome. RESULTS Only two Tunisian consanguineous pedigrees were enrolled in this study. Two boys were diagnosed with typical Sotos syndrome based on the three major clinical manifestations: specific facial dysmorphism, mental retardation and excessive growth including advanced bone age and macrocephaly. Chromosomes 5 in both pedigrees did not show structural abnormalities. During genetic counselling, parents were informed about the molecular testing options and the advantage of the exome sequencing. Furthermore, they were informed about the rate of cancer predisposition (3%) and the gains of neurologic and neuro-oncologic management, particularly regarding the intellectual disability and the increased risk of developing neural crest tumors, astrocytoma, glioma/glioblastoma and neuroblastoma cancer, during childhood. CONCLUSIONS Neurological pediatric malignancies are described in patients with Sotos syndrome, but the genotype-phenotype correlation is still unclear. It is suggested that NDS1 disruptions in Sotos patients trigger specific patterns of DNA methylation alterations leading to the development of cancer. Accurate molecular exploration is needed in the heterogeneous Sotos condition in order to improve the management according to the implicated gene and to benefit in the future from targeted therapies.