Biallelic variants in cause the most prevalent known recessive neurodevelopmental disorder.

We recently showed that mutations in and , two genes that are transcribed into small nuclear RNA (snRNA) components of the major spliceosome, are prevalent causes of dominant neurodevelopmental disorders (NDDs). By genetic association comparing 12,776 NDD cases with 56,064 controls, we now demonstrate the existence of a recessive form of syndrome that, in England, is even more common than the dominant form. We inferred log Bayes factors for dominant and recessive models of association of 14.

Expanding the Phenotypic Spectrum Associated with DPH5-Related Diphthamide Deficiency.

Background/objectives: Neurodevelopmental disorders (NDDs) represent a clinically diverse group of conditions that affect brain development, often leading to varying degrees of functional impairment. Many NDDs, particularly syndromic forms, are caused by genetic mutations affecting critical cellular pathways. Ribosomopathies, a subgroup of NDDs, are linked to defects in ribosomal function, including those involving the synthesis of diphthamide, a post-translational modification of translation elongation factor 2 (eEF2).

Missense variants in cause myo-tubulinopathies.

Tubulinopathies encompass a wide spectrum of disorders resulting from variants in genes encoding α- and β-tubulins, the key components of microtubules. While previous studies have linked or dominantly inherited missense variants to neurodegenerative phenotypes, including amyotrophic lateral sclerosis, frontotemporal dementia, hereditary spastic ataxia, and more recently, an isolated report of congenital myopathy, the full phenotypic and genotypic spectrum of -related disorders remains incompletely characterised. In this multi-centre study, we identified 13 novel missense variants in 31 individuals from 19 unrelated families.

Diagnosis of Angelman Syndrome, With 66 Years of Delay, Using Hypothesis-Free DNA Methylation Profiling.

Hypothesis-free DNA methylation profiling in a 66-year-old male with unexplained neurodevelopmental disorder enabled the exclusion of ZNF142-related disease (left panel) and led to a retrospective diagnosis of Angelman syndrome, highlighting the diagnostic potential of single-patient epigenetic screening (right panel).

Updated ACMG/AMP specifications for variant interpretation and gene curations from the ClinGen RASopathy expert panels.

Purpose: The ClinGen RASopathy (RAS) Variant Curation Expert Panel (VCEP) previously established RASopathy specifications to the American College of Medical Genetics and Genomics (ACMG) and Association of Molecular Pathology (AMP) variant classification framework for more consistent and accurate variant classification. Advances in the understanding of RASopathies and new clinical genetic testing algorithms required updated specifications.

Methods: The RAS Gene Curation Expert Panel recurated 6 gene-disease relationships, and the RAS VCEP evaluated the previous specifications to develop updated RASopathy specifications for the ACMG/AMP framework.

Biallelic SH2B3 germline variants are associated with a neonatal myeloproliferative disease and multisystemic involvement.

Known genetic disorders, such as Noonan syndrome and Down syndrome, can present in the neonatal period or early infancy with myeloproliferative disease (MPD) or abnormal myelopoiesis, which often self-resolves. This phenomenon results from an imbalance in differentiation and cell regulation caused by the genetic condition during perinatal hematopoiesis. Recently, SH2B3 variants have also been associated with neonatal MPD.

Biallelic loss-of-function variants in ZNF142 are associated with a robust DNA methylation signature affecting a limited number of genomic loci.

Biallelic inactivating variants in ZNF142 underlie a clinically variable neurodevelopmental disorder. ZNF142 is a zinc-finger transcription factor with potential roles on chromatin organization, implying a possible association of ZNF142 loss of function with perturbed genome-wide DNA methylation (DNAm) pattern. We performed EPIC array-based methylation profiling of peripheral blood-derived DNA samples from 27 individuals with biallelic ZNF142 inactivating variants, together with 6 heterozygous carriers and 40 controls.

Wnt/β-catenin activation by mutually exclusive FBXW11 and CTNNB1 hotspot mutations drives salivary basal cell adenoma.

Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) of the salivary gland are rare tumours that can be difficult to distinguish from each other and other salivary gland tumour subtypes. Using next-generation sequencing, we identify a recurrent FBXW11 missense mutation (p.F517S) in BCA that is mutually exclusive with the previously reported CTNNB1 p.

An Efficient Protocol to Assess ERK Activity Modulation in Early Zebrafish Noonan Syndrome Models via Live FRET Microscopy and Immunofluorescence.

RASopathies are genetic syndromes caused by ERK hyperactivation and resulting in multisystemic diseases that can also lead to cancer predisposition. Despite a broad genetic heterogeneity, germline gain-of-function mutations in key regulators of the RAS-MAPK pathway underlie the majority of the cases, and, thanks to advanced sequencing techniques, potentially pathogenic variants affecting the RAS-MAPK pathway continue to be identified. Functional validation of the pathogenicity of these variants, essential for accurate diagnosis, requires fast and reliable protocols, preferably in vivo.

Molecular Dynamics Simulations of the SPRED2 EVH-1 Domain Complexed with the GAP-Related Domain of Neurofibromin.

The homozygous Leu100Pro amino acid substitution in SPRED2, a protein negatively controlling RAS function, has recently been identified to be causally linked to a recessive form of Noonan syndrome. The amino acid substitution was documented to affect protein stability and cause a decreased and/or less stable interaction with neurofibromin, a RAS-specific GTPase activating protein negatively regulating RAS function. To further investigate the structural and functional impact of Leu100Pro, we structurally characterized the consequences of this change on the interaction of SPRED2 with neurofibromin, by 1 µn-long molecular dynamics (MD) simulations.

Update on the Clinical and Molecular Characterization of Noonan Syndrome and Other RASopathies: A Retrospective Study and Systematic Review.

RASopathies are a diverse group of genetic conditions caused by hyperactivation of the RAS-MAPK signaling pathway, mainly inherited in an autosomal dominant manner. They present with variable features such as short stature, congenital heart defects, facial dysmorphisms, and neurodevelopmental delays. This study retrospectively analyzed 143 cases from 2003 to 2022, aiming to improve genotype-phenotype correlation knowledge for personalized care.

Phenotypic Characterization of Seven Pediatric Patients Diagnosed With KAT6B -Related Disorders: Case Series and Review of the Literature.

Genitopatellar syndrome (GPS) and Say-Barber-Biesecker-Young-Simpson Syndrome (SBBYSS) are clinically distinct neurodevelopmental disorders caused by monoallelic pathogenic variants in KAT6B. In some cases, GPS and SBBYSS features can overlap, determining an intermediate phenotype. In the present study, we describe seven patients, four with a clinical diagnosis of SBBYSS and three presenting with an intermediate phenotype.

Variable Ophthalmologic Phenotypes Associated with Biallelic Loss-of-Function Variants in .

O-mannosylation is a post-translational modification required for the proper function of various proteins and critical for development and growth. encodes the enzyme O-linked-mannose β-1,2-N-acetylglucosaminyltransferase 1, which catalyzes the second step in the synthesis of α-dystroglycan O-mannosyl glycans. Among -related α-dystroglycanopathies, muscle-eye-brain (MEB) disease presents with congenital muscular dystrophy, structural brain abnormalities, and retinal dystrophy.

Riboflavin transporter deficiency: gene therapy as a new therapeutic strategy.

Riboflavin transporter deficiency syndrome (RTD) is a rare childhood-onset neurodegenerative disorder caused by mutations in and genes, encoding the riboflavin (RF) transporters hRFVT2 and hRFVT3. In the present study we focused on RTD Type 2, which is due to variants in gene. There is no cure for RTD patients and, although studies have reported clinical improvements with administration of RF, an effective treatment is still unavailable.

Expanding the mutational spectrum of ReNU syndrome: insights into 5' Stem-loop variants.

A narrow spectrum of heterozygous variants in RNU4-2, encoding the small nuclear RNA (snRNA) U4, underlies ReNU syndrome, a neurodevelopmental disorder (NDD) characterized by moderate to severe developmental delay (DD), intellectual disability (ID), a distinctive facial gestalt, and multisystem involvement. Pathogenic variants have primarily been reported within an 18-nt critical region contributing to stabilizing the U4/U6 snRNA duplex and proper spliceosome assembly. By combining whole genome sequencing reanalysis and targeted direct sequencing in 190 molecularly unexplained NDD cases, we report on five affected individuals carrying pathogenic/putative pathogenic RNU4-2 variants (2.

The Arg99Gln Substitution in HNRNPC Is Associated with a Distinctive Clinical Phenotype Characterized by Facial Dysmorphism and Ocular and Cochlear Anomalies.

Heterozygous variants in the heterogeneous nuclear ribonucleoprotein C gene () have recently been reported to cause intellectual developmental disorder-74 (MRD74), a neurodevelopmental disorder with no recurrent diagnostic handles. Affected individuals show variable, non-specific, and subtle dysmorphic features. The degree of developmental delay (DD)/intellectual disability (ID) is also wide, ranging from mild to severe.

CDK13-Related Disorder: Novel Insights From A Series of 27 Cases and Recommendations for Clinical Management.

In 2016, Sifrim and colleagues described the first group of patients carrying heterozygous pathogenic variants in CDK13 and sharing major clinical features mainly consisting of congenital heart defects, intellectual disability and peculiar facial features (Congenital Heart Defects, Dysmorphic Facial Features, and Intellectual Developmental Disorder; CHDFIDD, OMIM # 617360). This condition is generally referred to as CDK13-related disorder, and since then other reports have provided further clinical and molecular information. Here we describe a group of 27 previously unreported patients to more accurately profile the clinical spectrum associated with CDK13 variants, disclosing novel associated findings, such as complex craniosynostosis and variable skeletal features (e.

AUTS2-related syndrome: Insights from a large European cohort.

Purpose: AUTS2-related syndrome is characterized by developmental delay, autism spectrum disorder, and intellectual disability. From alternative promoters, AUTS2 encodes 2 distinct long and short isoforms encoding a putative transcriptional activator.

Methods: Through a European collaborative study, we collected clinical and genotype data on the largest AUTS2-related syndrome cohort of 58 patients harboring genomic rearrangements or single-nucleotide variants (SNVs).

Impact of pubertal timing on growth progression and final height in subjects affected by RASopathies.

Background: RASopathies, including Noonan syndrome and related disorders, are multisystem conditions caused by mutations in various genes encoding proteins involved in the RAS/MAPK signaling pathway resulting in increased signal flow. They are clinically characterized by failure to thrive, facial dysmorphisms, congenital heart defects, lymphatic malformations, skeletal anomalies, and variable cognitive impairment, with variable prevalence in the different conditions and subtypes. Pubertal development, which affects growth and final height, is often delayed in Noonan syndrome patients, though not universally.

Genomic Testing in Adults With Undiagnosed Rare Conditions: Improvement of Diagnosis Using Clinical Exome Sequencing as a First-Tier Approach.

Adult patients with undiagnosed genetic disorders suffer most from diagnostic delay and seldom appear in cohort studies investigating the diagnostic yield in medical genetic clinical practice. Here we present the results of the diagnostic activity performed in a referral center on 654 consecutive, unselected adult subjects presenting with molecularly unsolved conditions. More than 50% of the referred individuals were affected by syndromic or isolated intellectual disability.

Altered cytoskeleton dynamics in patient-derived iPSC-based model of PCDH19 clustering epilepsy.

Protocadherin 19 (PCDH19) is an adhesion molecule involved in cell-cell interaction whose mutations cause a drug-resistant form of epilepsy, named PCDH19-Clustering Epilepsy (PCDH19-CE, MIM 300088). The mechanism by which altered PCDH19 function drive pathogenesis is not yet fully understood. Our previous work showed that PCDH19 dysfunction is associated with altered orientation of the mitotic spindle and accelerated neurogenesis, suggesting a contribution of altered cytoskeleton organization in PCDH19-CE pathogenesis in the control of cell division and differentiation.

Genomic reanalysis of a pan-European rare-disease resource yields new diagnoses.

Genetic diagnosis of rare diseases requires accurate identification and interpretation of genomic variants. Clinical and molecular scientists from 37 expert centers across Europe created the Solve-Rare Diseases Consortium (Solve-RD) resource, encompassing clinical, pedigree and genomic rare-disease data (94.5% exomes, 5.

Molecular and clinical Insights into KMT2E-Related O'Donnell-Luria-Rodan syndrome in a novel patient cohort.

O'Donnell-Luria-Rodan (ODLURO) syndrome is an autosomal dominant neurodevelopmental disorder mainly characterized by global development delay/intellectual disability, white matter abnormalities, and behavioral manifestations. It is caused by pathogenic variants in the KMT2E gene. Here we report seven new patients with loss-of-function KMT2E variants, six harboring frameshift/nonsense changes, and one with a 7q22.