Le parcours diagnostique des enfants atteints d’Arthrogrypose Multiple Congénitale : description des pratiques actuelles à travers une cohorte monocentrique, et proposition de recommandations

Introduction: Arthrogryposis multiplex congenita (AMC) defines congenital contractures involving two or more body areas. The prevalence is estimated between 1/3000 and 1/12000. More than 400 conditions may lead to AMC through foetal hypo/a-kinesia, making the aetiological diagnosis challenging. The objective of this work was to describe the aetiological management of children with AMC and to propose recommendations in order to optimize clinical practices. Material and methods: We conducted a retrospective single centre observational study. Patients had been evaluated at least once at a paediatric age in Grenoble University Hospital from 2007 to 2019. After determining the diagnostic status of these patients, data on their diagnostic procedure were gathered. A literature review was performed for each paraclinical investigation to discuss their relevance in the light of patients’ diagnoses, scientific knowledge, and benefit/risk or cost/benefit ratio. Results: 125 patients were included, 43% had Amyoplasia, 26% had distal arthrogryposis, and 31% had other forms. A definitive aetiological diagnosis was available for 63% of cases. We propose a two-time diagnostic process : first, non-invasive investigations that aim at classifying patients into one of the three groups, and then specific investigations targeting a subset of patients according to the expected yield and invasiveness. Conclusion: The diagnostic management of AMC patients has to result from a multidisciplinary approach. With the use of next generation sequencing, the aetiological assessment will be facilitated, but a relevant phenotyping will be paramount to guide their interpretation.Introduction : L’Arthrogrypose Multiple Congénitale (AMC) correspond à des limitations articulaires touchant au moins deux niveaux. Sa prévalence est estimée entre 1/3000 et 1/12000. Le diagnostic étiologique est difficile car il en existe plus de 400 causes. L’objectif de ce travail est de décrire le parcours diagnostique des enfants atteints d’AMC et de proposer des recommandations afin d’optimiser les pratiques cliniques. Matériel et méthodes : Nous avons mené une étude rétrospective observationnelle monocentrique, incluant les enfants évalués au Centre Hospitalier Universitaire de Grenoble de 2007 à 2019. Nous avons collecté les informations sur leur parcours diagnostique, puis avons mené une revue de la littérature pour chaque investigation paraclinique afin d’en évaluer la pertinence à la lumière du diagnostic final des patients, des connaissances scientifiques, de leur bénéfices, risques et coûts. Résultats : Nous avons inclus un total de 125 patients, dont 43% cas d’Amyoplasie, 26% d’arthrogrypose distale et 31% d’autres formes. Un diagnostic étiologique était posé dans 63% des cas. Nous proposons une procédure diagnostique en deux temps: d’abord des investigations non invasives permettant d’orienter les patients vers l’un des trois groupes principaux, puis des investigations plus spécifiques avec des indications précises, en fonction de leur rendement attendu et de leur caractère invasif. Conclusion : L’approche diagnostique des enfants avec AMC doit résulter d’un travail pluridisciplinaire. L’utilisation croissante du séquençage de nouvelle génération facilitera cette démarche, mais le phénotypage restera essentiel pour guider leur interprétation

A Homozygous Ancestral SVA-Insertion-Mediated Deletion in WDR66 Induces Multiple Morphological Abnormalities of the Sperm Flagellum and Male Infertility.

International audienceMultiple morphological abnormalities of the sperm flagellum (MMAF) is a severe form of male infertility defined by the presence of a mosaic of anomalies, including short, bent, curled, thick, or absent flagella, resulting from a severe disorganization of the axoneme and of the peri-axonemal structures. Mutations in DNAH1, CFAP43, and CFAP44, three genes encoding axoneme-related proteins, have been described to account for approximately 30% of the MMAF cases reported so far. Here, we searched for pathological copy-number variants in whole-exome sequencing data from a cohort of 78 MMAF-affected subjects to identify additional genes associated with MMAF. In 7 of 78 affected individuals, we identified a homozygous deletion that removes the two penultimate exons of WDR66 (also named CFAP251), a gene coding for an axonemal protein preferentially localized in the testis and described to localize to the calmodulin- and spoke-associated complex at the base of radial spoke 3. Sequence analysis of the breakpoint region revealed in all deleted subjects the presence of a single chimeric SVA (SINE-VNTR-Alu) at the breakpoint site, suggesting that the initial deletion event was potentially mediated by an SVA insertion-recombination mechanism. Study of Trypanosoma WDR66's ortholog (TbWDR66) highlighted high sequence and structural analogy with the human protein and confirmed axonemal localization of the protein. Reproduction of the human deletion in TbWDR66 impaired flagellar movement, thus confirming WDR66 as a gene associated with the MMAF phenotype and highlighting the importance of the WDR66 C-terminal region

De novo SMARCA2 variants clustered outside the helicase domain cause a new recognizable syndrome with intellectual disability and blepharophimosis distinct from Nicolaides–Baraitser syndrome

International audiencePurpose: Nontruncating variants in SMARCA2, encoding a catalytic subunit of SWI/SNF chromatin remodeling complex, cause Nicolaides-Baraitser syndrome (NCBRS), a condition with intellectual disability and multiple congenital anomalies. Other disorders due to SMARCA2 are unknown.Methods: By next-generation sequencing, we identified candidate variants in SMARCA2 in 20 individuals from 18 families with a syndromic neurodevelopmental disorder not consistent with NCBRS. To stratify variant interpretation, we functionally analyzed SMARCA2 variants in yeasts and performed transcriptomic and genome methylation analyses on blood leukocytes.Results: Of 20 individuals, 14 showed a recognizable phenotype with recurrent features including epicanthal folds, blepharophimosis, and downturned nasal tip along with variable degree of intellectual disability (or blepharophimosis intellectual disability syndrome [BIS]). In contrast to most NCBRS variants, all SMARCA2 variants associated with BIS are localized outside the helicase domains. Yeast phenotype assays differentiated NCBRS from non-NCBRS SMARCA2 variants. Transcriptomic and DNA methylation signatures differentiated NCBRS from BIS and those with nonspecific phenotype. In the remaining six individuals with nonspecific dysmorphic features, clinical and molecular data did not permit variant reclassification.Conclusion: We identified a novel recognizable syndrome named BIS associated with clustered de novo SMARCA2 variants outside the helicase domains, phenotypically and molecularly distinct from NCBRS

Further delineation of auriculocondylar syndrome based on 14 novel cases and reassessment of 25 published cases

Auriculocondylar syndrome (ACS) is a rare craniofacial disorder characterized by mandibular hypoplasia and an auricular defect at the junction between the lobe and helix, known as a "Question Mark Ear" (QME). Several additional features, originating from the first and second branchial arches and other tissues, have also been reported. ACS is genetically heterogeneous with autosomal dominant and recessive modes of inheritance. The mutations identified to date are presumed to dysregulate the endothelin 1 signaling pathway. Here we describe 14 novel cases and reassess 25 published cases of ACS through a questionnaire for systematic data collection. All patients harbor mutation(s) in PLCB4, GNAI3, or EDN1. This series of patients contributes to the characterization of additional features occasionally associated with ACS such as respiratory, costal, neurodevelopmental, and genital anomalies, and provides management and monitoring recommendations

Mutations in CFAP43 and CFAP44 cause male infertility and flagellum defects in TrypanosomaTrypanosoma and human.

International audienceSpermatogenesis defects concern millions of men worldwide, yet the vast majority remains undiagnosed. Here we report men with primary infertility due to multiple morphological abnormalities of the sperm flagella with severe disorganization of the sperm axoneme, a microtubule-based structure highly conserved throughout evolution. Whole-exome sequencing was performed on 78 patients allowing the identification of 22 men with bi-allelic mutations in DNAH1 (n = 6), CFAP43 (n = 10), and CFAP44 (n = 6). CRISPR/Cas9 created homozygous CFAP43/44 male mice that were infertile and presented severe flagellar defects confirming the human genetic results. Immunoelectron and stimulated-emission-depletion microscopy performed on CFAP43 and CFAP44 orthologs in $Trypanosoma\ brucei$ evidenced that both proteins are located between the doublet microtubules 5 and 6 and the paraflagellar rod. Overall, we demonstrate that CFAP43 and CFAP44 have a similar structure with a unique axonemal localization and are necessary to produce functional flagella in species ranging from $Trypanosoma$ to human

De Novo SOX6 Variants Cause a Neurodevelopmental Syndrome Associated with ADHD, Craniosynostosis, and Osteochondromas.

SOX6 belongs to a family of 20 SRY-related HMG-box-containing (SOX) genes that encode transcription factors controlling cell fate and differentiation in many developmental and adult processes. For SOX6, these processes include, but are not limited to, neurogenesis and skeletogenesis. Variants in half of the SOX genes have been shown to cause severe developmental and adult syndromes, referred to as SOXopathies. We here provide evidence that SOX6 variants also cause a SOXopathy. Using clinical and genetic data, we identify 19 individuals harboring various types of SOX6 alterations and exhibiting developmental delay and/or intellectual disability; the individuals are from 17 unrelated families. Additional, inconstant features include attention-deficit/hyperactivity disorder (ADHD), autism, mild facial dysmorphism, craniosynostosis, and multiple osteochondromas. All variants are heterozygous. Fourteen are de novo, one is inherited from a mosaic father, and four offspring from two families have a paternally inherited variant. Intragenic microdeletions, balanced structural rearrangements, frameshifts, and nonsense variants are predicted to inactivate the SOX6 variant allele. Four missense variants occur in residues and protein regions highly conserved evolutionarily. These variants are not detected in the gnomAD control cohort, and the amino acid substitutions are predicted to be damaging. Two of these variants are located in the HMG domain and abolish SOX6 transcriptional activity in vitro. No clear genotype-phenotype correlations are found. Taken together, these findings concur that SOX6 haploinsufficiency leads to a neurodevelopmental SOXopathy that often includes ADHD and abnormal skeletal and other features