Laurent Pasquier

Background and ObjectivesDevelopmental and epileptic encephalopathies (DEEs) with early burst-suppression EEG (EIDEE-BS) are among the most severe neonatal epileptic syndromes, typically presenting...

Il est acquis que l’utilisation des tests génétiques fait partie des pratiques courantes de nombreuses spécialités médicales. Pourtant la réalisation d’un test génétique soulève des problématiques spécifiques qui impactent la trajectoire de vie des personnes, à court terme, mais aussi à long terme, en bousculant les notions de prévention, de prédiction, de santé, de maladie, tant pour le patient et que pour sa famille. Ces tests génétiques soulèvent des questions centrales pour les choix que doivent faire les individus et la société lors de leur mise en œuvre (respect des droits fondamentaux, gestion des résultats et de l’incertitude, équilibre entre le secret médical et le droit des tiers…). Il convient de se demander comment accompagner le développement rapide d’une médecine génomique, pour laquelle la plupart des médecins n’ont pas été spécifiquement formés. Analyser la façon dont ces professionnels intègrent ces tests génétiques à la relation soignante est essentiel pour préparer à un meilleur usage de la génomique par tous.Par le biais d’une approche multidisciplinaire alliant des médecins généticiens, des juristes, sociologues, spécialistes d’éthique, et associations de patients, nous avons mené une réflexion sur les enjeux médicaux, éthiques, sociologiques et juridiques dans le cadre de la réalisation des tests génétiques à l’échelle d’une population. Nous avons également mené une étude qualitative composée d’une série d’entretiens semi-structurés en focus groups auprès de 21 médecins spécialistes en neurologie et endocrinologie, autour de leurs pratiques en génétique.Sur les bases de ces réflexions et de cette étude qualitative, nous suggérons de mettre en œuvre une certaine forme de régulation avec la promotion d’une véritable politique d’accompagnement des pratiques médicales autour des tests génétiques en :1. Promouvant la recherche autour de l’utilité médicale des tests génétiques pour le patient et sa famille au regard des incertitudes liées au résultat notamment lorsqu’il s’agira de proposer des tests génétiques en population générale.2. Orientant les pratiques vers une approche systémique de nature pluridisciplinaire par équipe ou en réseau (incluant des spécialistes d’organes et des spécialistes généticiens cliniciens et biologistes) comme une arène de ressources efficace pour faire face aux incertitudes dans l’interprétation d’un résultat, aux situations limites du côté technique ou clinique et permettre, si besoin, la réalisation de consultations en binômes.3. Accumulant des éléments quantitatifs supplémentaires autour de ces pratiques, des éléments juridiques, économiques et de confrontations avec les professionnels de santé impliqués dans la médecine génomique pour faire évoluer le cadre réglementaire, qui n’apparait aujourd’hui que partiellement adapté à la réalisation de tests génétiques en population et aux pratiques médicales. Ce travail de fond parait indispensable afin d’éclairer le législateur avant toutes modifications lors d’une prochaine révision de loi relative à la Bioéthique.2. Favorisant une réelle autonomie des patients en évitant d’inclure la proposition de ce test génétique dans une procédure automatisée de soins. La seule réalisation d’un consentement écrit ne peut pas être de nature à justifier cette banalisation du test génétique compte tenu des enjeux associés aux résultats. Cette autonomie pourrait être accrue par une sensibilisation des médecins prescripteurs lors des sessions de formation médicale continue et par une meilleure acculturation de la génétique par le grand public.Au total ce dialogue entre les disciplines médico-techniques génétiques et les sciences humaines et sociales apparait pertinent dans la mesure où les enjeux sociétaux apparaissent particulièrement nombreux et sensibles. Cela serait de nature à proposer un accompagnement adéquat pour chaque personne et sa famille en génétique médicale.

Introduction International pilot projects focusing on next-generation sequencing in newborn screening (NBS), that is, genomic NBS (gNBS), have been established thanks to continuous therapeutic progress and the massive development of new genetic technologies with rapidly decreasing costs. Given the highly encouraging results of the French SeDeN project regarding anticipated acceptability among professionals and parents, it is now appropriate to launch a similar pilot project in France, in collaboration with other international initiatives under the International Consortium on Newborn Sequencing framework. Methods and analysis PERIGENOMED is a large-scale project designed to provide the first concrete evidence on the relevance of gNBS in France. It includes two clinical trials. We present here the design chosen for the first clinical trial (PERIGENOMED-CLINICS 1). PERIGENOMED-CLINICS 1 aims to assess the feasibility, real-world acceptability, psychosocial impact and organisational pathways of panel-based genomic newborn screening in France, involving 2500 participants. Solo-GS targeting two lists of gene–disease dyads responsible for treatable (list 1; 400 genes, 171 diseases/group of diseases) or actionable (list 2 optional; 407 genes, 218 diseases/group of diseases) rare and severe early-onset diseases will be proposed in five health institutions. Ancillary social and impact studies will also be included. Ethics and dissemination All study procedures have been reviewed and approved by relevant French ethics committees and regulatory authorities (CPP Est II-2024-A02224-43, 1 January 2025). Results of the project will be disseminated through peer-reviewed publications, national and international conferences, and public engagement initiatives, in coordination with stakeholders. Trial registration number NCT06875089.

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. Altogether, we identified 145 previously unreported probands with (likely) pathogenic variants in RNU4-2 and 21 individuals with de novo and/or recurrent variants in RNU5B-1 and RNU5A-1, encoding U5. Pathogenic variants typically arose de novo on the maternal allele and cluster in regions critical for splicing. RNU4-2 variants mainly localize to two structures, the stem III and T-loop/quasi-pseudoknot, which position the U6 ACAGAGA box for 5′ splice site recognition and associate with different phenotypic severity. RNU4-2 variants result in specific defects in alternative 5′ splice site usage and methylation patterns (episignatures) that correlate with variant location and clinical severity. This study establishes RNU5B-1 as a neurodevelopmental disorder gene, suggests RNU5A-1 as a strong candidate and highlights the role of de novo variants in snRNAs.

GJB2 and GJB6 variants, encoding Cx26 and Cx30 respectively, are the most frequently involved genes commonly contributing to hereditary hearing loss either isolated or in combination with skin abnormalities. GJB6 variations are classically associated with two distinct conditions: non‐syndromic hearing loss and hidrotic ectodermal dysplasia, type Clouston, the latter typically not involving deafness.Method: Whole genome sequencing (WGS) was used to find genetic variants after clinical features of a 13‐year‐old female patient were recorded.Results: In this report, we describe the association of congenital hearing loss and ectodermal anomalies (palmoplantar keratoderma, knuckle pads, and nail dystrophy) in a female with the ENST00000647029.1 (GJB6): c.175G>A (p.(Gly59Arg)) GJB6 variant. As a result, we report on the third case of individuals showing this same missense variant and syndromic hearing loss.Conclusion: This study underscores the overlapping phenotypes observed in patients with the p.Gly59Arg variant in the GJB6 gene. The findings suggest a continuum of phenotypic presentations for this variant, with the key clinical features being the combination of congenital hearing loss and hyperkeratosis.

Rare genetic variants in ARID2 are responsible for a recently described neurodevelopmental condition called ARID2-related disorder (ARID2-RD). ARID2 belongs to PBAF, a unit of the SWI/SNF complex, which is a chromatin remodeling complex. This work aims to further delineate the phenotypic spectrum of ARID2-RD, providing clinicians with additional data for better care and aid in the future diagnosis of this condition. We obtained the genotypes and phenotypes of 27 previously unreported individuals with ARID2-RD and compared this series with findings in the literature. We also assessed peripheral blood DNA methylation profiles in individuals with ARID2-RD compared to episignatures of controls, unresolved cases, and other neurodevelopmental disorders. The main clinical features of ARID2-RD are developmental delay, speech disorders, intellectual disability (ID), behavior problems, short stature, and various dysmorphic and ectodermal features. Genome-wide differential methylation analysis revealed a global hypermethylated profile in ARID2-RD that could aid in reclassifying variants of uncertain significance. Our study doubles the number of reported individuals with ARID2 pathogenic variants to 53. It confirms loss-of-function as a pathomechanism and shows the absence of a clear genotype-phenotype correlation. We provide evidence for a unique DNA methylation episignature for ARID2-RD and further delineate the ARID2-associated phenotype.

Variants in RNU4-2 , encoding the small nuclear RNA (snRNA) U4, were recently identified as a major cause of neurodevelopmental disorders (ReNU syndrome). Here, we investigated de novo variants in 50 snRNAs in a French cohort of 23,649 individuals with rare disorders and collected data of additional patients through an international collaboration. Altogether, we identified 133 probands with pathogenic or likely pathogenic variants in RNU4-2 and 15 individuals with de novo and/or recurrent variants in constrained regions of RNU5B-1 , one of five genes encoding U5. These variants cluster in evolutionarily conserved regions of U4 and U5 essential for splicing. RNU4-2 variants affecting stem III are associated with milder phenotypes than those in the T-loop (quasi-pseudoknot). Phaseable variants associated with severe phenotypes occurred on the maternal allele. Individuals with RNU4-2 variants show specific defects in alternative 5’ splice site usage, correlating with variant location and clinical severity. Additionally, we report an episignature associated with severe ReNU syndrome. This study further highlights the importance of de novo variants in snRNAs and establishes RNU5B-1 as a new neurodevelopmental disorder gene.

DNA polymerase subunit gamma (POLG) deficiency is likely the most frequent cause of nuclear-encoded mitochondrial disorders. POLG-related disorders reportedly constitute a spectrum of overlapping phenotypes from infancy to late adulthood. We retrospectively reviewed natural histories for 40 children carrying biallelic pathogenic POLG variants. The patients were identified by the French coordinating center for mitochondrial disorders (CARAMMEL), making this a large monocentric series on childhood-onset POLG deficiency. Three patterns of clinical course and survival were observed, distinguished by main category of symptoms: neurologic, hepatic, and gastrointestinal. A total of 24 patients needed urgent neurointensive care for tonic-clonic seizures, myoclonic epilepsy, and status epilepticus, occasionally precipitated by valproate administration. Other neurologic symptoms included dystonia, cerebellar ataxia, and peripheral neuropathy. We report 6 POLG-deficient patients with polyradiculoneuropathy mimicking subacute Guillain-Barré syndrome and provide postgadolinium MRI evidence of diffuse cranial nerve root and cauda equina enhancement, suggesting these disorders have an inflammatory component. Children presenting with enteral nervous system involvement had vomiting, gastroparesis, and chronic intestinal pseudo-obstruction. They had later ages of onset and lived much longer. Primarily, hepatic presentations had the earliest onset and shortest survivals. Secondary hepatic failure was frequently precipitated by valproate administration given before diagnosis to patients with focal impaired awareness seizures or absence of seizures. These POLG deficiencies were often fatal, with age at death ranging from 3 months to 10 years, with a significant difference in survival between the 3 clinical forms; 6 of the 40 children did survive. No genotype-phenotype correlations were found for the 3 clinical course types. The study demonstrates the prevalence of neurologic presentation and the extent of central, peripheral, and autonomous nervous system involvement in 60% of patients. Most of the patients with early onset and rapidly fatal hepatic failure did not live long enough to develop neurologic symptoms. The study revealed a new clinical form of POLG deficiency presenting with neurodigestive symptoms with longer lifespan. We also propose that POLG deficiency should be considered in children presenting with unexplained polyradiculoneuropathy, demyelinating neuropathy, and elevated CSF protein. Finally, valproate administration remains a notable cause of avoidable death in POLG-deficient patients.

Tubulin, one of the most abundant cytoskeletal building blocks, has numerous isotypes in metazoans encoded by different conserved genes. Whether these distinct isotypes form cell type– and context-specific microtubule structures is poorly understood. Based on a cohort of 12 patients with primary ciliary dyskinesia as well as mouse mutants, we identified and characterized variants in the TUBB4B isotype that specifically perturbed centriole and cilium biogenesis. Distinct TUBB4B variants differentially affected microtubule dynamics and cilia formation in a dominant-negative manner. Structure-function studies revealed that different TUBB4B variants disrupted distinct tubulin interfaces, thereby enabling stratification of patients into three classes of ciliopathic diseases. These findings show that specific tubulin isotypes have distinct and nonredundant subcellular functions and establish a link between tubulinopathies and ciliopathies.

Background and Aims: Pediatric acute liver failure (PALF) is a life-threatening condition. In Europe, the main causes are viral infections (12%–16%) and inherited metabolic diseases (14%–28%). Yet, in up to 50% of cases the underlying etiology remains elusive, challenging clinical management, including liver transplantation. We systematically studied indeterminate PALF cases referred for genetic evaluation by whole-exome sequencing (WES), and analyzed phenotypic and biochemical markers, and the diagnostic yield of WES in this condition. Approach and Results: With this international, multicenter observational study, patients (0–18 y) with indeterminate PALF were analyzed by WES. Data on the clinical and biochemical phenotype were retrieved and systematically analyzed. Results: In total, 260 indeterminate PALF patients from 19 countries were recruited between 2011 and 2022, of whom 59 had recurrent PALF. WES established a genetic diagnosis in 37% of cases (97/260). Diagnostic yield was highest in children with PALF in the first year of life (41%), and in children with recurrent acute liver failure (64%). Thirty-six distinct disease genes were identified. Defects in NBAS (n=20), MPV17 (n=8), and DGUOK (n=7) were the most frequent findings. When categorizing, the most frequent were mitochondrial diseases (45%), disorders of vesicular trafficking (28%), and cytosolic aminoacyl-tRNA synthetase deficiencies (10%). One-third of patients had a fatal outcome. Fifty-six patients received liver transplantation. Conclusions: This study elucidates a large contribution of genetic causes in PALF of indeterminate origin with an increasing spectrum of disease entities. The high proportion of diagnosed cases and potential treatment implications argue for exome or in future rapid genome sequencing in PALF diagnostics.