Search

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber disease, is a dominant inherited vascular disorder. The clinical diagnosis is based on the Curaçao criteria and pathogenic variants in the ENG and ACVRL1 genes are responsible for most cases of HHT. Four families with a negative targeted gene panel and selected by a multidisciplinary team were selected and whole-genome sequencing was performed according to the recommendations of the French National Plan for Genomic Medicine. Structural variations were confirmed by standard molecular cytogenetic analysis (FISH). In two families with a definite diagnosis of HHT, we identified two different paracentric inversions of chromosome 9, both disrupting the ENG gene. These inversions are considered as pathogenic and causative for the HHT phenotype of the patients. This is the first time structural variations are reported to cause HHT. As such balanced events are often missed by exon-based sequencing (panel, exome), structural variations may be an under-recognized cause of HHT. Genome sequencing for the detection of these events could be suggested for patients with a definite diagnosis of HHT and in whom no causative pathogenic variant was identified., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Background: The EPIGENE network was created in 2014 by four multidisciplinary teams composed of geneticists, pediatric neurologists and neurologists specialized in epileptology and neurophysiology. The ambition of the network was to harmonize and improve the diagnostic strategy of Mendelian epileptic disorders using next-generation sequencing, in France. Over the years, five additional centers have joined EPIGENE and the network has been working in close collaboration, since 2018, with the French reference center for rare epilepsies (CRéER)., Results: Since 2014, biannual meetings have led to the design of four successive versions of a monogenic epilepsy gene panel (PAGEM), increasing from 68 to 144 genes. A total of 4035 index cases with epileptic disorders have been analyzed with a diagnostic yield of 31% (n = 1265/4035). The top 10 genes, SCN1A, KCNQ2, STXBP1, SCN2A, SCN8A, PRRT2, PCDH19, KCNT1, SYNGAP1, and GRIN2A, account for one-sixth of patients and half of the diagnoses provided by the PAGEM., Conclusion: These results suggest that a gene-panel approach is an efficient first-tier test for the genetic diagnosis of Mendelian epileptic disorders. In a near future, French patients with "drug-resistant epilepsies with seizure-onset in the first two-years of life" can benefit from whole-genome sequencing (WGS), as a second line genetic screening with the implementation of the 2025 French Genomic Medicine Plan. The EPIGENE network has also promoted scientific collaborations on genetic epilepsies within CRéER., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Transcription factor IID is a multimeric protein complex that is essential for the initiation of transcription by RNA polymerase II. One of its critical components, the TATA-binding protein-associated factor 2, is encoded by the gene TAF2. Pathogenic variants of this gene have been shown to be responsible for the Mental retardation, autosomal recessive 40 syndrome. This syndrome is characterized by severe intellectual disability, postnatal microcephaly, pyramidal signs and thin corpus callosum. Until now, only three families have been reported separately. Here we report four individuals, from two unrelated families, who present with severe intellectual disability and global developmental delay, postnatal microcephaly, feet deformities and thin corpus callosum and who carry homozygous TAF2 missense variants detected by Exome Sequencing. Taken together, our findings and those of previously reported subjects allow us to further delineate the clinical phenotype associated with TAF2 biallelic mutations., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

With the development of next generation sequencing, beyond identifying the cause of manifestations that justified prescription of the test, other information with potential interest for patients and their families, defined as secondary findings (SF), can be provided once patients have given informed consent, in particular when therapeutic and preventive options are available. The disclosure of such findings has caused much debate. The aim of this work was to summarize all opinion-based studies focusing on SF, so as to shed light on the concerns that this question generate. A review of the literature was performed, focusing on all PubMed articles reporting qualitative, quantitative or mixed studies that interviewed healthcare providers, participants, or society regarding this subject. The methodology was carefully analysed, in particular whether or not studies made the distinction between actionable and non-actionable SF, in a clinical or research context. From 2010 to 2016, 39 articles were compiled. A total of 14,868 people were interviewed (1259 participants, 6104 healthcare providers, 7505 representatives of society). When actionable and non-actionable SF were distinguished (20 articles), 92% of respondents were keen to have results regarding actionable SF (participants: 88%, healthcare providers: 86%, society: 97%), against 70% (participants: 83%, healthcare providers: 62%, society: 73%) for non-actionable SF. These percentages were slightly lower in the specific situation of children probands. For respondents, the notion of the «patient's choice» is crucial. For healthcare providers, the importance of defining policies for SF among diagnostic lab, learning societies and/or countries is outlined, in particular regarding the content and extension of the list of actionable genes to propose, the modalities of information, and the access to information about adult-onset diseases in minors. However, the existing literature should be taken with caution, since most articles lack a clear definition of SF and actionability, and referred to hypothetical scenarios with limited information to respondents. Studies conducted by multidisciplinary teams involving patients with access to results are sadly lacking, in particular in the medium term after the results have been given. Such studies would feed the debate and make it possible to measure the impact of such findings and their benefit-risk ratio., (Copyright © 2018. Published by Elsevier Masson SAS.)

Alazami syndrome (AS) (MIM# 615071) is an autosomal recessive microcephalic primordial dwarfism (PD) with recognizable facial features and severe intellectual disability due to depletion or loss of function variants in LARP7. To date, 15 patients with AS have been reported. Here we describe two consanguineous Algerian sisters with Alazami PD due to LARP7 homozygous pathogenic variants detected by whole exome sequencing. By comparing these two additional cases with those previously reported, we strengthen the key features of AS: severe growth restriction, severe intellectual disability and some distinguishing facial features such as broad nose, malar hypoplasia, wide mouth, full lips and abnormally set teeth. We also report significant new findings enabling further delineation of this syndrome: disproportionately mild microcephaly, stereotypic hand wringing and severe anxiety, thickened skin over the hands and feet, and skeletal, eye and heart malformations. From previous reviews, we summarize the main etiologies of PD according to the involved mechanisms and cellular pathways, highlighting their clinical core features., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Background and Objective: Whole-exome sequencing (WES) has now entered medical practice with powerful applications in the diagnosis of rare Mendelian disorders. Although the usefulness and cost-effectiveness of WES have been widely demonstrated, it is essential to reduce the diagnostic turnaround time to make WES a first-line procedure. Since 2011, the automation of laboratory procedures and advances in sequencing chemistry have made it possible to carry out diagnostic whole genome sequencing from the blood sample to molecular diagnosis of suspected genetic disorders within 50 h. Taking advantage of these advances, the main objective of the study was to improve turnaround times for sequencing results., Methods: WES was proposed to 29 patients with severe undiagnosed disorders with developmental abnormalities and faced with medical situations requiring rapid diagnosis. Each family gave consent. The extracted DNA was sequenced on a NextSeq500 (Illumina) instrument. Data were analyzed following standard procedures. Variants were interpreted using in-house software. Each rare variant affecting protein sequences with clinical relevance was tested for familial segregation., Results: The diagnostic rate was 45% (13/29), with a mean turnaround time of 40 days from reception of the specimen to delivery of results to the referring physician. Besides permitting genetic counseling, the rapid diagnosis for positive families led to two pre-natal diagnoses and two inclusions in clinical trials., Conclusions: This pilot study demonstrated the feasibility of rapid diagnostic WES in our primary genetics center. It reduced the diagnostic odyssey and helped provide support to families., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)