Publications by authors named "Vincent Michaud"

Introduction: There is few data that investigate the genetic underpinnings of idiopathic foveal hypoplasia and assess its potential overlap with albinism-related gene variants in a cohort devoid of familial albinism history.

Methods: This cross-sectional study included 19 participants diagnosed with idiopathic foveal hypoplasia, confirmed via optical coherence tomography (OCT). We detailed ophthalmic evaluations and genotyping using a panel of 33 genes related to foveal hypoplasia.

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The major spliceosome contains five small nuclear RNAs (snRNAs; U1, U2, U4, U5 and U6) essential for splicing. Variants in RNU4-2, encoding U4, cause a neurodevelopmental disorder called ReNU syndrome. We investigated de novo variants in 50 snRNA-encoding genes in a French cohort of 23,649 individuals with rare disorders and gathered additional cases through international collaborations.

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Purpose: Albinism is a genetic disorder characterized by a defect in melanin biosynthesis. Ophthalmological and dermatological impairments vary according to the patient genotype and are highly heterogenous. Recently, variants in the DCT gene were showed to be responsible for a new type of oculocutaneous albinism (OCA) named OCA8.

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Pigmentation is orchestrated by hundreds of genes involved in cellular functions going from early developmental fate of pigment cells to melanin synthesis. The Two Pore Channel 2 (TPC2) a Ca2+ and Na+ channel acidifies melanosomal pH and thus inhibits pigmentation. A young patient was recently reported with generalized hypopigmentation but uneventful ocular examination, caused by the de novo heterozygous TPCN2 variant c.

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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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Introduction: Classically, Usher syndrome is characterized by the association of sensorineural hearing loss (SNHL), retinitis pigmentosa (RP) and possible vestibular dysfunction. Pathogenic bi-allelic variants in cause atypical autosomal recessive Usher syndrome, which is associated with SNHL and photoreceptors dysfunction without vestibular signs. To date, only 19 scattered descriptions have been reported.

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Oculocutaneous albinism type 1 is caused by variants in the TYR (tyrosinase) gene. We describe a family with two affected sibs who inherited the pathogenic missense TYR variant c.1146C > A;p.

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Article Synopsis
  • * Researchers analyzed data from over 1,100 individuals with albinism to investigate the combined effects of two specific genetic variants, showing that their presence together significantly increases the likelihood of an albinism diagnosis.
  • * Findings from various cohorts suggest that this combination of variants not only leads to an increased diagnosis rate but also correlates with changes in visual acuity and retinal thickness, paving the way for further research into genetic interactions in Mendelian disorders.
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  • PI4KA-related disorder is marked by a variety of neurological and gastrointestinal issues, including spasticity, developmental challenges, and recurrent infections, with specific attention given to the impact on B-cell function and immunodeficiency in some patients. * -
  • The study involved analyzing 13 patients with PI4KA variants, revealing common traits such as B-cell deficiency and hypogammaglobulinemia, alongside significant changes in B-cell subsets and functioning due to metabolic disruptions. * -
  • Findings indicate that mutations in PI4KA lead to disturbances in lipid production and metabolic pathways in B cells, fostering mitochondrial dysfunction and abnormal immune responses, suggesting a critical role of PI4KA in B-cell differentiation and health. *
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  • - Albinism is caused by a variety of genes (21 identified), with most cases following an autosomal recessive inheritance pattern, though one form is X-linked; about 70% of cases can be diagnosed through genetic analysis.
  • - Of the undiagnosed cases, roughly 15% carry one pathogenic variant but may have undiscovered variants in non-coding regions; this research involved sequencing a group of 122 heterozygous patients.
  • - From the study, 12 patients received additional diagnoses based on non-coding variants that affected RNA splicing, highlighting the need to investigate non-coding regions to improve diagnostic rates for genetic diseases like albinism.
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  • - AHR gene defects are linked to a rare disorder characterized by infantile nystagmus and foveal hypoplasia, as demonstrated in a case study of a 6-year-old girl with a novel genetic variant.
  • - Comprehensive eye examinations, including VEP and electroretinography, revealed significant visual impairments and specific patterns in the patient's visual processing.
  • - Over an 11-year follow-up, the patient's visual acuity improved despite the initial diagnosis of severe ocular conditions, highlighting potential for positive outcomes in similar cases.
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  • - TOKAS (Tonne-Kalscheuer syndrome) is a rare genetic disorder linked to multiple congenital anomalies, predominantly affecting males, and only 7 prenatal cases were previously documented among 41 patients.
  • - A study identified 11 new cases from 6 French families through collaboration, revealing common features like diaphragmatic hernia, sex development differences, and various malformations, along with previously unreported conditions.
  • - This research marks the first comprehensive fetal cohort for TOKAS, enhancing understanding of its clinical traits and genetic variants, with a significant recurrence of a specific genetic mutation noted in many cases.
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Albinism is a phenotypically and genetically heterogeneous condition characterized by a variable degree of hypopigmentation and by ocular features leading to reduced visual acuity. Whereas numerous genotypic studies have been conducted throughout the world, very little is known about the genotypic spectrum of albinism in Africa and especially in sub-Saharan Western Africa. Here we report the analysis of all known albinism genes in a series a 23 patients originating from Mali.

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  • Crimean-Congo haemorrhagic fever (CCHF) is a serious viral disease transmitted from animals to humans, characterized by fever and bleeding symptoms.
  • The virus has been found in ticks in Spain and antibodies in livestock in Corsica, raising concerns about its presence in France.
  • During 2022-2023, 155 ticks carrying the Crimean-Congo haemorrhagic fever virus (CCHFV) were identified in southern France from horses and cattle.
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Purpose: BCL11B-related disorder (BCL11B-RD) arises from rare genetic variants within the BCL11B gene, resulting in a distinctive clinical spectrum encompassing syndromic neurodevelopmental disorder, with or without intellectual disability, associated with facial features and impaired immune function. This study presents an in-depth clinico-biological analysis of 20 newly reported individuals with BCL11B-RD, coupled with a characterization of genome-wide DNA methylation patterns of this genetic condition.

Methods: Through an international collaboration, clinical and molecular data from 20 individuals were systematically gathered, and a comparative analysis was conducted between this series and existing literature.

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  • The study focuses on albinism, a genetic condition where melanin production is affected, highlighting the variability in its forms and their impact on ocular health.
  • A retrospective analysis was performed on 127 patients with oculocutaneous albinism from a specific hospital in France, assessing their genetic data and visual acuity.
  • The findings revealed no significant differences in visual acuity across the main forms of albinism, but significant differences in ametropia were observed, along with a high prevalence of grade 4 foveal hypoplasia among patients, independent of the gene involved.
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Oculocutaneous albinism type 2 (OCA2) is the second most frequent form of albinism and represents about 30% of OCA worldwide. As with all types of OCA, patients present with hypopigmentation of hair and skin, as well as severe visual abnormalities. We focused on a subgroup of 29 patients for whom genetic diagnosis was pending because at least one of their identified variants in or around exon 10 of OCA2 is of uncertain significance (VUS).

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Albinism is a clinically and genetically heterogeneous group of conditions characterised by visual abnormalities and variable degrees of hypopigmentation. Multiple studies have demonstrated the clinical utility of genetic investigations in individuals with suspected albinism. Despite this, the variation in the provision of genetic testing for albinism remains significant.

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Pathogen transfers between wild and domestic animals and between animals and humans are increasing. Their dramatic consequences for public and veterinary health as well as for conservation call for innovative and user-friendly methods for pathogen surveillance in wildlife. Xenosurveillance, a method based on the use of invertebrates (e.

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  • Common obesity is a major global health issue, but studying its rare monogenic forms has provided insights into the genetic mechanisms involved, particularly those affecting appetite regulation in the brain.
  • A variant in the POU3F2 gene, linked to neurodevelopmental disorders and obesity, was identified in a family showing symptoms of both syndromic obesity and autism spectrum disorder.
  • Research suggests that dysfunctional variants of POU3F2 contribute to difficulties in appetite control and weight gain during adolescence, indicating its role not just in monogenic forms, but possibly also in common obesity cases.
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  • The study aims to describe the phenotypic and genotypic spectrum of a neurodevelopmental disorder linked to a specific gene implicated in periventricular nodular heterotopia (PVNH).
  • Researchers examined 17 individuals with variants, identifying several types of genetic mutations and their effects on brain structure and function.
  • Findings highlighted a range of symptoms, including intellectual disability, seizures, microcephaly, and various neurological and sensory defects, confirming the gene's role in this autosomal dominant syndrome characterized by abnormal neuronal migration.
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  • - The study focuses on patients with KCNT2-related developmental epileptic encephalopathy (DEE) and identifies 25 individuals with various pathogenic variants, revealing a range of symptoms including intellectual disabilities and epilepsy.
  • - Researchers conducted in-depth genetic analysis and functional studies on 14 novel KCNT2 variants, finding 19 pathogenic variants in total, including both gain-of-function and loss-of-function features.
  • - The findings suggest that different KCNT2 variants exhibit distinct pharmacological responses, underlining the importance of tailored drug treatments based on specific genetic and functional profiles.
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Albinism is a genetic disorder, present worldwide, caused by mutations in genes affecting melanin production or transport in the skin, hair and eyes. To date, mutations in at least 20 different genes have been identified. Oculo-cutaneous Albinism type IV (OCA4) is the most frequent form in Asia but has been reported in all populations, including Europeans.

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