Publications by authors named "Bertrand Isidor"

Objective: Monoallelic variants in the transient receptor potential melastatin-related type 3 gene (TRPM3) have been associated with neurodevelopmental manifestations, but knowledge on the clinical manifestations and treatment options is limited. We characterized the clinical spectrum, highlighting particularly the epilepsy phenotype, and the effect of treatments.

Methods: We analyzed retrospectively the phenotypes and genotypes of 43 individuals with TRPM3 variants, acquired from GeneMatcher and collaborations (n = 21), and through a systematic literature search (n = 22).

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RICTOR is a key component of the mTORC2 signaling complex which is involved in the regulation of cell growth, proliferation and survival. RICTOR is highly expressed in neurons and is necessary for brain development. Here, we report eight unrelated patients presenting with intellectual disability and/or development delay and carrying variants in the RICTOR gene.

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  • The TAOK proteins are important kinases involved in various cellular functions and are linked to neurodevelopmental disorders (NDDs) like those caused by TAOK1 and TAOK2 variants.
  • A study analyzed clinical and genetic data from individuals with these variants, revealing that TAOK1 variants lead to significant neurodevelopmental issues and some novel characteristics, while TAOK2 variants are tied to neurodevelopmental abnormalities, autism, and obesity.
  • This research expands the understanding of these disorders by presenting the largest cohort of individuals with TAOK1-NDD and identifying new variants and phenotypes associated with both TAOK1 and TAOK2.
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  • RORA is a gene linked to the development and function of the cerebellum, and this study explores the largest group of individuals with RORA-related neurodevelopmental disorders (RORA-NDD).
  • The study involved 40 participants with various pathogenic variants of RORA, revealing a range of clinical features including developmental and intellectual disabilities, as well as cerebellar symptoms that can vary in onset and severity.
  • Findings indicate that certain missense variants are associated with more severe cerebellar issues, and common elements of RORA-NDD include developmental disabilities, cerebellar symptoms, and different types of myoclonic epilepsy.
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The Houge type of X-linked syndromic intellectual developmental disorder (MRXSHG) encompasses a spectrum of neurodevelopmental disorders characterized by intellectual disability (ID), language/speech delay, attention issues, and epilepsy. These conditions arise from hemizygous or heterozygous deletions, along with point mutations, affecting CNKSR2, a gene located at Xp22.12.

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While mostly de novo truncating variants in SCAF4 were recently identified in 18 individuals with variable neurodevelopmental phenotypes, knowledge on the molecular and clinical spectrum is still limited. We assembled data on 50 novel individuals with SCAF4 variants ascertained via GeneMatcher and personal communication. With detailed evaluation of clinical data, in silico predictions and structural modeling, we further characterized the molecular and clinical spectrum of the autosomal dominant SCAF4-associated neurodevelopmental disorder.

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Introduction: Heterozygous pathogenic variants in NTRK2 (HGNC: 8032) have been associated with global developmental delay. However, only scattered cases have been described in small or general studies. The aim of our work was to consolidate our understanding of NTRK2-related disorders and to delineate the clinical presentation METHODS: We report extended cohort of 44 affected individuals, of whom 19 are from the literature and 25 were previously unreported.

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encodes a human long noncoding RNA (lncRNA) adjacent to , a coding gene in which de novo loss-of-function variants cause developmental and epileptic encephalopathy. Here, we report our findings in three unrelated children with a syndromic, early-onset neurodevelopmental disorder, each of whom had a de novo deletion in the locus. The children had severe encephalopathy, shared facial dysmorphisms, cortical atrophy, and cerebral hypomyelination - a phenotype that is distinct from the phenotypes of patients with haploinsufficiency.

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  • Osteoporosis is a skeletal disorder leading to increased fracture risk, and when it affects young individuals, it often indicates genetic causes related to early-onset osteoporosis (EOOP).
  • Over 577 patients with primary osteoporosis were studied using next-generation sequencing of 21 bone fragility-related genes, revealing that around 18% had a genetic basis, primarily linked to the LRP5 gene.
  • A rare finding included 17 patients with a variant in the PLS3 gene, suggesting the involvement of dominant X-linked osteoporosis, predominantly affecting males, but also identified severe cases in females, pointing toward possible genetic interactions.
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  • - This study examines the link between rare variants in the cullin-3 ubiquitin ligase (CUL3) gene and neurodevelopmental disorders (NDDs), gathering data from multiple centers to explore genetic mutations and their clinical impacts.
  • - Researchers identified 37 individuals with CUL3 variants, most of which result in loss-of-function (LoF), leading to intellectual disabilities and possibly autistic traits; specific mechanisms affecting protein stability were also investigated.
  • - The findings enhance the understanding of NDDs associated with CUL3 mutations, suggesting that LoF variants are the main cause, which could help inform future diagnostics and treatment strategies.
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  • Researchers studied mutations in a gene that affects a key protein involved in cell signaling, which is linked to severe health issues like impaired immunity in patients.
  • The mutations were found to disrupt normal cell behavior by promoting excessive cell growth and responses to immune signals, specifically T cell receptor stimulation.
  • The mutant protein was shown to interfere with a regulatory protein, leading to heightened activity of important signaling pathways that contribute to cell growth and survival.
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  • The study investigates a specific genetic variant in the IP3 receptor that results in a significant disorder affecting multiple systems, characterized by immunodeficiency and disturbed calcium release in cells.
  • The variant (c.7570C>T, p.Arg2524Cys) leads to cellular defects, particularly impacting T cells, and is shown to affect calcium regulation and mitochondrial function, evidenced in laboratory models.
  • Patients exhibited a range of symptoms beyond immunodeficiency, such as ectodermal dysplasia and short stature, suggesting that this genetic mutation plays a unique and broader role in disease compared to previously documented cases.
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  • Glutathione synthetase deficiency is a rare genetic disorder caused by mutations in the GSS gene, leading to varying severity levels, from mild hemolytic anemia to severe neurological issues and even neonatal death.
  • A study on two fetal siblings revealed multiple congenital anomalies, such as limb malformations, cleft palate, and heart defects, linked to specific genetic variants in the GSS gene.
  • Genome sequencing and analysis indicated that these genetic variants likely caused disruptions in protein expression and metabolic processes, suggesting a broader range of phenotypic effects associated with glutathione synthetase deficiency.
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  • * Many forms of intellectual disability prevalent globally are monogenic diseases, with a notable portion linked to genes in the ubiquitin-proteasome system, which regulates protein maintenance.
  • * A new category of neurodevelopmental disorders, termed "neurodevelopmental proteasomopathies," is emerging, characterized by cognitive impairments and various clinical features, though the underlying molecular mechanisms are still not well understood.
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Autism spectrum disorder (ASD) is a neurodevelopmental disorder (NDD) that affects approximately 4% of males and 1% of females in the United States. While causes of ASD are multi-factorial, single rare genetic variants contribute to around 20% of cases. Here, we report a case series of seven unrelated probands (6 males, 1 female) with ASD or another variable NDD phenotype attributed to de novo heterozygous loss of function or missense variants in the gene LARP1 (La ribonucleoprotein 1).

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  • Prenatal exome sequencing (pES) is increasingly used to diagnose fetuses with structural defects, identifying additional conditions in about 30% who have normal chromosomal microarray analysis (CMA).
  • A study categorized prenatal phenotypes for fetuses with pathogenic variants, finding typical features in 67.9% of cases, while uncommon or unreported features complicated some interpretations.
  • Recommendations include standardizing prenatal feature descriptions, enhancing follow-up practices, and collecting larger datasets to improve pES analysis.
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  • * A significant challenge arises from "silent" Mendelian genes (SMGs), which show insufficient expression in patient tissues; 36% of these genes are linked to neurological disorders, highlighting the need for improved gene expression techniques.
  • * Researchers developed two methods—CRISPR-based gene activation and fibroblast-to-neuron transdifferentiation—to induce SMG expression, achieving remarkable success and enabling further investigation of variants in genes linked to specific diseases.
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  • * These disorders result in developmental issues, particularly affecting neural development and causing physical abnormalities like craniofacial defects and heart malformations.
  • * The paper suggests that neural crest cells, which play a crucial role in forming craniofacial structures and heart components, may be particularly affected by disruptions in protein homeostasis, urging further research for potential treatments.
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Microtubule associated proteins (MAPs) are widely expressed in the central nervous system, and have established roles in cell proliferation, myelination, neurite formation, axon specification, outgrowth, dendrite, and synapse formation. We report eleven individuals from seven families harboring predicted pathogenic biallelic, de novo, and heterozygous variants in the NAV3 gene, which encodes the microtubule positive tip protein neuron navigator 3 (NAV3). All affected individuals have intellectual disability (ID), microcephaly, skeletal deformities, ocular anomalies, and behavioral issues.

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  • - POLG deficiency is the most common cause of nuclear-encoded mitochondrial disorders, leading to a range of overlapping symptoms from infancy to adulthood, as seen in a study of 40 children with biallelic pathogenic variants.
  • - The study identified three main clinical patterns (neurologic, hepatic, gastrointestinal), with 24 patients requiring urgent care mainly due to severe neurologic issues like seizures and epilepsy.
  • - Most children with hepatic symptoms had the earliest onset and shortest survival rates, while those with gastrointestinal issues had milder symptoms and lived longer; overall, the prognosis was poor, with many fatalities occurring by age 10.
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  • Leucine aminoacyl tRNA-synthetase 1 (LARS1)-deficiency is linked to infantile liver failure syndrome and presents with symptoms like acute liver failure, neurological issues, and seizures.
  • Cranial MRIs show characteristic changes in brain structures during encephalopathic episodes, with infections often triggering these episodes, which involve seizures and impaired consciousness.
  • The study emphasizes the importance of managing infections and ensuring proper nutrition, along with recommending vaccinations to prevent severe episodes during flu infections.
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Primary proteasomopathies have recently emerged as a new class of rare early-onset neurodevelopmental disorders (NDDs) caused by pathogenic variants in the PSMB1, PSMC1, PSMC3, or PSMD12 proteasome genes. Proteasomes are large multi-subunit protein complexes that maintain cellular protein homeostasis by clearing ubiquitin-tagged damaged, misfolded, or unnecessary proteins. In this study, we have identified PSMD11 as an additional proteasome gene in which pathogenic variation is associated with an NDD-causing proteasomopathy.

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Clinical geneticists and syndromologists have traditionally focused on identifying syndromes in children. However, there is a growing acknowledgment of the need to describe adult phenotypes. This article provides an overview of the evolving phenotypes of rare genetic syndromes into adulthood, elucidating its challenges, opportunities, and future perspectives.

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Intracellular trafficking involves an intricate machinery of motor complexes including the dynein complex to shuttle cargo for autophagolysosomal degradation. Deficiency in dynein axonemal chains as well as cytoplasmic light and intermediate chains have been linked with ciliary dyskinesia and skeletal dysplasia. The cytoplasmic dynein 1 heavy chain protein (DYNC1H1) serves as a core complex for retrograde trafficking in neuronal axons.

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Chung-Jansen syndrome is a neurodevelopmental disorder characterized by intellectual disability, behavioral problems, obesity and dysmorphic features. It is caused by pathogenic variants in the PHIP gene that encodes for the Pleckstrin homology domain-interacting protein, which is part of an epigenetic modifier protein complex. Therefore, we hypothesized that PHIP haploinsufficiency may impact genome-wide DNA methylation (DNAm).

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