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Heterozygous missense HTRA1 mutations have been associated with an autosomal dominant cerebral small vessel disease (CSVD) whereas the pathogenicity of heterozygous HTRA1 stop codon variants is unclear. We performed a targeted high throughput sequencing of all known CSVD genes, including HTRA1, in 3853 unrelated consecutive CSVD patients referred for molecular diagnosis. The frequency of heterozygous HTRA1 mutations leading to a premature stop codon in this patient cohort was compared with their frequency in large control databases. An analysis of HTRA1 mRNA was performed in several stop codon carrier patients. Clinical and neuroimaging features were characterized in all probands. Twenty unrelated patients carrying a heterozygous HTRA1 variant leading to a premature stop codon were identified. A highly significant difference was observed when comparing our patient cohort with control databases: gnomAD v3.1.1 [P = 3.12 × 10−17, odds ratio (OR) = 21.9], TOPMed freeze 5 (P = 7.6 × 10−18, OR = 27.1) and 1000 Genomes (P = 1.5 × 10−5). Messenger RNA analysis performed in eight patients showed a degradation of the mutated allele strongly suggesting a haploinsufficiency. Clinical and neuroimaging features are similar to those previously reported in heterozygous missense mutation carriers, except for penetrance, which seems lower. Altogether, our findings strongly suggest that heterozygous HTRA1 stop codons are pathogenic through a haploinsufficiency mechanism. Future work will help to estimate their penetrance, an important information for genetic counselling.

Pediatric cardiomyopathies are clinically heterogeneous heart muscle disorders associated with significant morbidity and mortality for which substantial evidence for a genetic contribution was previously reported. We present a detailed molecular investigation of a cohort of 231 patients presenting with primary cardiomyopathy below the age of 18 years.Cases with pediatric cardiomyopathies were analyzed using a next-generation sequencing (NGS) workflow based on a virtual panel including 57 cardiomyopathy-related genes.This molecular approach led to the identification of 69 cases (29.9% of the cohort) genotyped as a carrier of at least one pathogenic or likely pathogenic variant. Fourteen patients were carriers of two mutated alleles (homozygous or compound heterozygous) on the same cardiomyopathy-related gene, explaining the severe clinical disease with early-onset cardiomyopathy. Homozygous TNNI3 pathogenic variants were detected for five unrelated neonates (2.2% of the cohort), with four of them carrying the same truncating variant, i.e. p.Arg69Alafs*8.Our study confirmed the importance of genetic testing in pediatric cardiomyopathies. Discovery of novel pathogenic variations is crucial for clinical management of affected families, as a positive genetic result might be used by a prospective parent for prenatal genetic testing or in the process of pre-implantation genetic diagnosis.

Background and ObjectivesAfter clinical evaluation, the molecular diagnosis of type 1 facioscapulohumeral dystrophy (FSHD1) relies in most laboratories on the detection of a shortened D4Z4 array at the 4q35 locus by Southern blotting. In many instances, this molecular diagnosis remains inconclusive and requires additional experiments to determine the number of D4Z4 units or identify somatic mosaicism, 4q-10q translocations, and proximal p13E-11 deletions. These limitations highlight the need for alternative methodologies, illustrated by the recent emergence of novel technologies such as molecular combing (MC), single molecule optical mapping (SMOM), or Oxford Nanopore-based long-read sequencing providing a more comprehensive analysis of 4q and 10q loci. Over the last decade, MC revealed a further increasing complexity in the organization of the 4q and 10q distal regions in patients with FSHD withcis-duplication of D4Z4 arrays in approximately 1%–2% of cases.MethodsBy using MC, we investigated in our center 2,363 cases for molecular diagnosis of FSHD. We also evaluated whether previously reportedcis-duplications might be identified by SMOM using the Bionano EnFocus FSHD 1.0 algorithm.ResultsIn our cohort of 2,363 samples, we identified 147 individuals carrying an atypical organization of the 4q35 or 10q26 loci. Mosaicism is the most frequent category followed bycis-duplications of the D4Z4 array. We report here chromosomal abnormalities of the 4q35 or 10q26 loci in 54 patients clinically described as FSHD, which are not present in the healthy population. In one-third of the 54 patients, these rearrangements are the only genetic defect suggesting that they might be causative of the disease. By analyzing DNA samples from 3 patients carrying a complex rearrangement of the 4q35 region, we further showed that the SMOM direct assembly of the 4q and 10q alleles failed to reveal these abnormalities and lead to negative results for FSHD molecular diagnosis.DiscussionThis work further highlights the complexity of the 4q and 10q subtelomeric regions and the need of in-depth analyses in a significant number of cases. This work also highlights the complexity of the 4q35 region and interpretation issues with consequences on the molecular diagnosis of patients or genetic counseling.

An expanding number of genetic syndromes are linked to mutations in genes encoding factors that guide chromatin organization. Recently, distinct genetic syndromes have been linked to mutations in theSMCHD1gene. However, the function of this non-canonical SMC protein remains partly defined in Human tissues. To address this question, we determined its epi-signature in type 2 Facio Scapulo Humeral Dystrophy (FSHD2) and Bosma Arhinia and Microphtalmia Syndrome (BAMS) linked to heterozygous mutations in this gene. By combining RNA-Seq, DNA methylation profiling and ChIP-Seq, we showed that SMCHD1 regulates repressed chromatin but alsocis-regulatory elements and enhancers. Our results emphasize dual functions for SMCHD1, in chromatin compaction, chromatin insulation and gene regulation with variable outcomes and targets depending on tissues. We propose that altered DNA methylation and long-range chromatin organization at a number of loci required for development and tissue differentiation, trigger variegated gene expression in rare genetic diseases linked to heterozygousSMCHD1mutations.

International audience; BackgroundRiluzole has been reported to be beneficial in patients with cerebellar ataxia; however, effectiveness in individual subtypes of disease is unclear due to heterogeneity in participants' causes and stages of disease. Our aim was to test riluzole in a single genetic disease, spinocerebellar ataxia type 2.MethodsWe did a randomised, double-blind, placebo-controlled, multicentre trial (the ATRIL study) at eight national reference centres for rare diseases in France that were part of the Neurogene National Reference Centre for Rare Diseases. Participants were patients with spinocerebellar ataxia type 2 with an age at disease onset of up to 50 years and a scale for the assessment and rating of ataxia (SARA) score of at least 5 and up to 26. Patients were randomly assigned centrally (1:1) to receive either riluzole 50 mg orally or placebo twice per day for 12 months. Two visits, at baseline and at 12 months, included clinical measures and 3T brain MRI. The primary endpoint was the proportion of patients whose SARA score improved by at least 1 point. Analyses were done in the intention-to-treat population (all participants who were randomly assigned) and were done with only the observed data (complete case analysis). This trial is registered at ClinicalTrials.gov (NCT03347344) and has been completed.FindingsBetween Jan 18, 2018, and June 14, 2019, we enrolled 45 patients. 22 patients were randomly assigned to receive riluzole and 23 to receive placebo. Median age was 42 years (IQR 36–57) in the riluzole group and 49 years (40–56) in the placebo group and 23 (51%) participants were women. All participants presented with moderate-stage disease, characterised by a median SARA score of 13·5 (IQR 9·5–16·5). The primary endpoint, SARA score improvement of at least 1 point after 12 months, was observed in seven patients (32%) in the treated group versus nine patients (39%) in the placebo group, with a mean difference of −10·3% (95% CI −37·4% to 19·2%; p=0·75). SARA score showed a median increase (ie, worsening) of 0·5 points (IQR −1·5 to 1·5) in the riluzole group versus 0·3 points (−1·0 to 2·5) in the placebo group (p=0·70). No serious adverse event was reported in the riluzole-treated group whereas four patients in placebo group had a serious adverse event (hepatic enzyme increase, fracture of external malleolus, rectorrhagia, and depression). The number of patients with adverse events was similar in both groups (riluzole 16 [73%] patients vs placebo 19 [83%] patients; p=0·49).InterpretationWe were able to recruit 45 patients moderately affected by spinocerebellar ataxia type 2 for this trial. Riluzole did not improve clinical or radiological outcomes in these patients. However, our findings provide data on progression of spinocerebellar ataxia type 2 that might prove to be valuable for the design of other clinical trials.

International audience; Fabry disease (FD) is an X-linked genetic disease due to pathogenic variants in GLA. The phenotype varies depending on the GLA variant, alpha-galactosidase residual activity, patient's age and gender and, for females, X chromosome inactivation. Over 1000 variants have been identified, many through screening protocols more susceptible to disclose non-pathogenic variants or variants of unknown significance (VUS). This, together with the non-specificity of some FD symptoms, challenges physicians attempting to interpret GLA variants. The traditional way to interpreting pathogenicity is based on a combined approach using allele frequencies, genomic databases, global and disease-specific clinical databases, and in silico tools proposed by the American College of Medical Genetics and Genomics. Here, a panel of FD specialists convened to study how expertise may compare with the traditional approach. Several GLA VUS, highly controversial in the literature (p.Ser126Gly, p.Ala143Thr, p.Asp313Tyr), were re-analyzed through reviews of patients' charts. The same was done for pathogenic GLA variants with some specificities. Our data suggest that input of geneticists and physicians with wide expertise in disease phenotypes, prevalence, inheritance, biomarkers, alleles frequencies, disease-specific databases, and literature greatly contribute to a more accurate interpretation of the pathogenicity of variants, bringing a significant additional value over the traditional approach.

Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecular features of drug release are so far unknown. Here, we resolved two ATP-Mg2+-bound outward-facing (OF) conformations of the Bacillus subtilis (homodimeric) BmrA, one by X-ray crystallography without drug, and another by single-particle cryo-EM with rhodamine 6G (R6G). Two R6G molecules bind to the drug-binding cavity at the level of the outer leaflet, between transmembrane (TM) helices 1-2 of one monomer and TM5’-6’ of the other. R6G induces a rearrangement of TM1-2, highlighting a flexibility that was confirmed by H/D exchange and molecular dynamics simulations. The latter also shows a fast post-release occlusion of the cavity driven by hydrophobicity. Altogether, these data support a new swing mechanism for drug transport.

Background Early diagnosis of cardiac amyloidosis (CA) is challenging. Several echocardiographic (echo) parameters have been proposed to differentiate CA from hypertrophic cardiomyopathy (HCM), but their respective value is debated. CA is known to be characterized by a more severe decline in longitudinal deformation parameters as compared with radial function parameters (LVEF). This characteristic justified the use of the ejection fraction strain ratio (EFSR) in these patients. However, since longitudinal dysfunction usually predominates in basal segments (apical sparing), we postulated that a new parameter focusing on LVEF and basal LV deformation (EFBSR: ejection fraction basal strain ratio) will even better discriminate patients with CA from HCM than EFSR and other echo or strain parameters. Purpose To compare the accuracy of deformation-based echocardiographic parameters for detecting CA in a population with different causes of LV hypertrophy. Methods and results We included 237 subjects, of which 89 patients with CA (77±10.7 years, 72% male, EF: 56.2±12.8%, and mean interventricular septum: 18.3±3.5 mm), 137 patients with hypertrophic cardiomyopathies (HCM), 52 patients with severe aortic stenosis with myocardial remodeling, 20 patients with arterial hypertension, and 20 control patients. Conventional echocardiographic parameters and strain-derived ratios (Relative apical sparing (RELAPS), Ejection Fraction Strain Ratio (EFSR) and EFBSR) were analyzed. EFBSR and RELAPS presented with the best performance to discriminate CA from other causes of hypertrophy (Area Under the Curve (AUC): 0.880; 95% CI: 0.830–0.929 and 0.903; 95% CI: 0.863–0.943 respectively) (p-value=0.3). In our study, among all the parameters, RELAPS had the best specificity (89.8% vs 88.3% for EFBSR), whereas EFBSR had the best sensitivity (78.7% vs 76.4% for RELAPS). EFBSR ranged from 35.25 to 1.83 and the cutoff value to differentiate CA from other hypertrophic cardiopathy was an EFBSR >7.75. Conclusions Our study demonstrates that in patients with LV hypertrophy, a new deformation parameter, the ejection fraction basal strain ratio (EFBSR) can accurately differentiate CA from other causes of myocardial thickening and can be used in routine practice for screening. Funding Acknowledgement Type of funding sources: None.

International audience; Mitral valve prolapse (MVP) is a common valvular heart defect with variable outcomes. Several studies reported MVP as an underestimated cause of life-threatening arrhythmias and sudden cardiac death (SCD), mostly in young adult women. Herein, we report a clinical and genetic investigation of a family with bileaflet MVP and a history of syncopes and resuscitated sudden cardiac death. Using family based whole exome sequencing, we identified two missense variants in the SCN5A gene. A rare variant SCN5A:p.Ala572Asp and the well-known functional SCN5A:p.His558Arg polymorphism. Both variants are shared between the mother and her daughter with a history of resuscitated SCD and syncopes, respectively. The second daughter with prodromal MVP as well as her healthy father and sister carried only the SCN5A:p.His558Arg polymorphism. Our study is highly suggestive of the contribution of SCN5A mutations as the potential genetic cause of the electric instability leading to ventricular arrhythmias in familial MVP cases with syncope and/or SCD history.

Over the recent years, the SMCHD1 (Structural Maintenance of Chromosome flexible Hinge Domain Containing 1) chromatin-associated factor has triggered increasing interest after the identification of variants in three rare and unrelated diseases, type 2 Facio Scapulo Humeral Dystrophy (FSHD2), Bosma Arhinia and Microphthalmia Syndrome (BAMS), and the more recently isolated hypogonadotrophic hypogonadism (IHH) combined pituitary hormone deficiency (CPHD) and septo-optic dysplasia (SOD). However, it remains unclear why certain mutations lead to a specific muscle defect in FSHD while other are associated with severe congenital anomalies. To gain further insights into the specificity of SMCHD1 variants and identify pathways associated with the BAMS phenotype and related neural crest defects, we derived induced pluripotent stem cells from patients carrying a mutation in this gene. We differentiated these cells in neural crest stem cells and analyzed their transcriptome by RNA-Seq. Besides classical differential expression analyses, we analyzed our data using MOGAMUN, an algorithm allowing the extraction of active modules by integrating differential expression data with biological networks. We found that in BAMS neural crest cells, all subnetworks that are associated with differentially expressed genes converge toward a predominant role for AKT signaling in the control of the cell proliferation-migration balance. Our findings provide further insights into the distinct mechanism by which defects in neural crest migration might contribute to the craniofacial anomalies in BAMS., Marseille Maladies Rares (MarMaRa) Institute French Investissement D’avenir Programme; NUS PYP Start-up Grant; Association Française contre les Myopathies; Fondation Maladies Rares; French Ministry of Education Fellowship; FSH Society; Excellence Initiative of Aix-Marseille University A*Midex; National Research Foundation; Branco Weiss Foundation; EMBO Young Investigator; Agency for Science & Technology and Research (A*STAR) Use-Inspired Basic Research (UIBR) Grant

International audience; Background: Few data exist concerning genotype-phenotype relationships in left ventricular noncompaction (LVNC).Methods and results: From a multicenter French Registry, we report the genetic and clinical spectrum of 95 patients with LVNC, and their genotype-phenotype relationship. Among the 95 LVNC, 45 had at least 1 mutation, including 14 cases of mutation in ion channel genes. In a complementary analysis including 16 additional patients with ion channel gene mutations, for a total of 30 patients with ion channel gene mutation, we found that those patients had higher median LV ejection fraction (60% vs 40%; P < .001) and more biventricular noncompaction (53.1% vs 18.5%; P < .001) than the 81 other patients with LVNC. Among them, both the 19 patients with an HCN4 mutation and the 11 patients with an RYR2 mutation presented with a higher LV ejection fraction and more frequent biventricular noncompaction than the 81 patients with LVNC but with no mutation in the ion channel gene, but only patients with HCN4 mutation presented with a lower heart rate.Conclusions: Ion channel gene mutations should be searched systematically in patients with LVNC associated with either bradycardia or biventricular noncompaction, particularly when LV systolic function is preserved. Identifying causative mutations is of utmost importance for genetic counselling of at-risk relatives of patients affected by LVNC.

Les 19 et 20 juin 2019, la conférence internationale sur la recherche dans la dystrophie facio-scapulo-humérale (FSHD) a eu lieu à Marseille. La rencontre rassemblant 180 participants, médecins, scientifiques et patients était organisée au Palais du Pharo à Marseille. Ce site historique emblématique surplombant le Vieux Port et faisant face à Notre Dame de la Garde a été construit dans la seconde moitié du XIXe siècle par Napoléon III pour son épouse, l’impératrice Eugénie.

Purpose Recent evolution of sequencing technologies and the development of international standards in variant interpretation have profoundly changed the diagnostic approaches in clinical genetics. As a consequence, many variants that were initially claimed to be disease-causing can be now reclassified as benign or uncertain in light of the new data available. Unfortunately, the misclassified variants are still present in the scientific literature and variant databases, greatly interfering with interpretation of diagnostic sequencing results. Despite the urgent need, large-scale efforts to update the classifications of these variants are still not sufficient. Methods We retrospectively analyzed 176 DYSF gene variants that were identified in dysferlinopathy patients referred to the Marseille Medical Genetics Department for diagnostic sequencing since 2001. Results We reclassified all variants into five-tier American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) pathogenicity classes, revealing changed pathogenicity for 17 variants. We then updated the information for the variants that have been previously published in the variant database and submitted 46 additional DYSF variants. Conclusion Besides direct benefit for dysferlinopathy diagnostics, our study contributes to the much needed effort to reanalyze variants from previously published cohorts and to work with curators of variant databases to update the entries for erroneously classified variants. Unlabelled Image

International audience; Purpose: Diagnosis of inherited ataxia and related diseases represents a real challenge given the tremendous heterogeneity and clinical overlap of the various causes. We evaluated the efficacy of molecular diagnosis of these diseases by sequencing a large cohort of undiagnosed families.Methods: We analyzed 366 unrelated consecutive patients with undiagnosed ataxia or related disorders by clinical exome-capture sequencing. In silico analysis was performed with an in-house pipeline that combines variant ranking and copy-number variant (CNV) searches. Variants were interpreted according to American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines.Results: We established the molecular diagnosis in 46% of the cases. We identified 35 mildly affected patients with causative variants in genes that are classically associated with severe presentations. These cases were explained by the occurrence of hypomorphic variants, but also rarely suspected mechanisms such as C-terminal truncations and translation reinitiation.Conclusion: A significant fraction of the clinical heterogeneity and phenotypic overlap is explained by hypomorphic variants that are difficult to identify and not readily predicted. The hypomorphic C-terminal truncation and translation reinitiation mechanisms that we identified may only apply to few genes, as it relies on specific domain organization and alterations. We identified PEX10 and FASTKD2 as candidates for translation reinitiation accounting for mild disease presentation.

Few data exist concerning genotype-phenotype relationships in left ventricular noncompaction (LVNC).From a multicenter French Registry, we report the genetic and clinical spectrum of 95 patients with LVNC, and their genotype-phenotype relationship. Among the 95 LVNC, 45 had at least 1 mutation, including 14 cases of mutation in ion channel genes. In a complementary analysis including 16 additional patients with ion channel gene mutations, for a total of 30 patients with ion channel gene mutation, we found that those patients had higher median LV ejection fraction (60% vs 40%; P.001) and more biventricular noncompaction (53.1% vs 18.5%; P.001) than the 81 other patients with LVNC. Among them, both the 19 patients with an HCN4 mutation and the 11 patients with an RYR2 mutation presented with a higher LV ejection fraction and more frequent biventricular noncompaction than the 81 patients with LVNC but with no mutation in the ion channel gene, but only patients with HCN4 mutation presented with a lower heart rate.Ion channel gene mutations should be searched systematically in patients with LVNC associated with either bradycardia or biventricular noncompaction, particularly when LV systolic function is preserved. Identifying causative mutations is of utmost importance for genetic counselling of at-risk relatives of patients affected by LVNC.

Predictive genetic testing (PGT) is offered to asymptomatic relatives at risk of hereditary heart disease, but the impact of result disclosure has been little studied. We evaluated the psychosocial impacts of PGT in hereditary heart disease, using self-report questionnaires (including the State-Trait Anxiety Inventory) in 517 adults, administered three times to the prospective cohort (PCo: n = 264) and once to the retrospective cohort (RCo: n = 253). The main motivations for undergoing PGT were &ldquo, to remove doubt&rdquo, and &ldquo, for their children&rdquo, The level of anxiety increased between pre-test and result appointments (p &lt, 0.0001), returned to baseline after the result (PCo), and was moderately elevated at 4.4 years (RCo). Subjects with a history of depression or with high baseline anxiety were more likely to develop anxiety after PGT result (p = 0.004 and p &lt, 0.0001, respectively), whatever it was. Unfavourable changes in professional and/or family life were observed in 12.4% (PCo) and 18.7% (RCo) of subjects. Few regrets about PGT were expressed (0.8% RCo, 2.3% PCo). Medical benefit was not the main motivation, which emphasises the role of pre/post-test counselling. When PGT was performed by expert teams, the negative impact was modest, but careful management is required in specific categories of subjects, whatever the genetic test result.

International audience; Background: Diagnosis of left ventricular non-compaction (LVNC) is challenging, and different imaging techniques propose different criteria.Aim: To compare the value of two-dimensional transthoracic echocardiography (2D-TTE) and cardiac magnetic resonance (CMR) criteria in diagnosing LVNC, and to test a new trabecular quantification method obtained by 2D-TTE, exploring its relationship with CMR non-compacted mass quantification.Methods: From a multicentre French study, we selected 48 patients with LVNC and 20 with dilated cardiomyopathy (DCM) who underwent 2D-TTE and CMR. Current 2D-TTE (Jenni et al.) and CMR criteria (Petersen et al., Jacquier et al.), were tested. A new 2D-TTE method of trabecular quantification (percentage of trabecular area) was also proposed, and compared with current criteria.Results: The best cut-off values for the diagnosis of LVNC were a non-compacted/compacted ratio≥2.3 (Petersen et al.), a trabeculated left ventricular mass≥20% (Jacquier et al.) and a non-compacted/compacted ratio≥1.8 (Jenni et al.). Lowering the threshold for the criterion of Jenni et al. from>2 to ≥1.8 improved its sensitivity from 69% to 98%. The 2D-TTE percentage of trabecular area was 25.9±8% in the LVNC group vs. 9.9±4.4% in the DCM group (P2 to ≥1.8 is necessary to improve LVNC diagnosis in patients with left ventricular dysfunction. A new 2D-TTE trabecular quantification method improves TTE diagnosis of LVNC.

Molecular defects in type 1 facioscapulohumeral muscular dystrophy (FSHD) are caused by a heterozygous contraction of the D4Z4 repeat array from 1 to 10 repeat units (RUs) on 4q35. This study compared (1) the phenotype and severity of FSHD1 between patients carrying 6&ndash, 8 vs. 9&ndash, 10 RUs, (2) the amount of methylation in different D4Z4 regions between patients with FSHD1 with different clinical severity scores (CSS). This cross-sectional multicenter study was conducted to measure functional scales and for genetic analysis. Patients were classified into two categories according to RUs: Group 1, 6&ndash, 8, Group 2, 9&ndash, 10. Methylation analysis was performed in 27 patients. A total of 99 carriers of a contracted D4Z4 array were examined. No significant correlations between RUs and CSS (r = 0.04, p = 0.73) and any of the clinical outcome scales were observed between the two groups. Hypomethylation was significantly more pronounced in patients with high CSS (&gt, 3.5) than those with low CSS (&lt, 1.5) (in DR1 and 5P), indicating that the extent of hypomethylation might modulate disease severity. In Group 1, the disease severity is not strongly correlated with the allele size and is mostly correlated with the methylation of D4Z4 regions.

Facioscapulohumeral dystrophy (FSHD), one of the most common hereditary neuromuscular disorders, is associated with a complex combination of genetic variations at the subtelomeric 4q35 locus. As molecular diagnosis relying on Southern blot (SB) might be challenging in some cases, molecular combing (MC) was recently developed as an additional technique for FSHD diagnosis and exploration of the genomic organization of the 4q35 and 10q26 regions. In complement to the usual SB, we applied MC in a large cohort of 586 individuals with clinical FSHD. In 332 subjects, the two 4q alleles were normal in size, allowing exclusion of FSHD1 while we confirmed FSHD1 in 230 patients. In 14 patients from 10 families, we identified a recurrent complex heterozygous rearrangement at 4q35 consisting of a duplication of the D4Z4 array and a 4qA haplotype, irresolvable by the SB technique. In five families, we further identified variations in the SMCHD1 gene. Impact of the different mutations was tested using a minigene assay and we analyzed DNA methylation after sodium bisulfite modification and NGS sequencing. We discuss the involvement of this rearrangement in FSHD since all mutations in SMCHD1 are not associated with D4Z4 hypomethylation and do not always segregate with the disease.

Introduction Hereditary heart diseases are most often characterized by autosomal dominant inheritance and delayed cardiac expression. Predictive genetic testing (PGT) is offered to asymptomatic relatives to allow targeted medical care with early therapeutics in order to reduce the risk of complications. Purpose The aim of this study was to evaluate the psychological and socio-professional impact of predictive genetic testing in hereditary heart diseases through a prospective and retrospective study. Methods & results This multicentric French study involved 20 expert centers in hereditary heart diseases. We included 517 adult relatives (42.3 ± 16.7 years, 60.6% females) who performed PGT (prospective study: n = 264, retrospective study: n = 253). The opinion and experience were collected via auto-questionnaires, at various moments in the prospective study, with different items and validated scales (STAI and IES). In the prospective study, family history was characterized by cardiomyopathy (88.4%) and channelopathies (11.6%). The main motivations for performing the test were: “to remove doubt” (65.3%), “for children” (64.0%), “to benefit from medical supervision” (34.9%). A mutation was present in 39.4% of relatives. No regret was expressed after testing (only 2.3% regrets). The result did not lead to a socio-professional change or family relationship change in 60.7%. Among those who had a change, it was perceived as unfavorable for only 3%. The level of anxiety (STAI) increases before the test result and decreased to return to baseline. Subjects with depression history were more likely to develop anxiety at long-term after multivariate analyses (P = 0.004). Conclusions Our results show that contrary to a widespread opinion, the medical benefit was not the main motivation for predictive genetic testing. In most cases, no or marginal adverse psychological and socio-professional impact of genetic testing was observed when performed by a team expert in predictive testing.

Background Mitral valve prolapse (MVP) is a frequent and heterogeneous valve desease. To date, mutations of only DCSH1 and FLNA have been identified in non-syndromic MVP but account for a small subset of cases. Purpose Our study aims to identify new genetic variants in non syndromic MVP. Methods We performed whole-exome sequencing in a family including a one year-old female patient with a severe mitral regurgitation due to a complex MVP and her unaffected parents. Results We identified a missense mutation in a gene known to be involved in cardiomyopathies but not in MVP. No mutation was found in DCSH1 and FLNA. The unaffected mother carried the same mutation as the index case. Functional studies on a mouse model showed that this gene is expressed in cells contributing to the mitral subvalvular apparatus development. Among thirteen patients with cardiomyopathy associated with mutation of the same gene, four had concomitant MVP. Conclusion Our study identified a candidate gene for MVP potentially associated with cardiomyopathy.

The small-fiber polyneuropathies (SFN) are a class of diseases in which the small thin myelinated (Aδ) and/or unmyelinated (C) fibers within peripheral nerves malfunction and can degenerate. SFN usually begins in the farthest, most-vulnerable axons, so distal neuropathic pain and symptoms from micro-vascular dysregulation are common. It is well known in adults, e.g. from diabetes, human immunodeficiency virus, or neurotoxins, but considered extremely rare in children, linked mostly with pathogenic genetic variants in voltage-gated sodium channels. However, increasing evidence suggests that pediatric SFN is not rare, and that dysimmunity is the most common cause. Because most pediatric neurologists are unfamiliar with SFN, we report the diagnosis and management of 5 Swiss children, aged 6–11y, who presented with severe paroxysmal burning pain in the hands and feet temporarily relieved by cooling—the erythromelalgia presentation. Medical evaluations revealed autoimmune diseases in 3 families and 3/5 had preceding or concomitant infections. The standard diagnostic test (PGP9.5-immunolabeled lower-leg skin biopsy) confirmed SFN diagnoses in 3/4, and autonomic function testing (AFT) was abnormal in 2/3. Blood testing for etiology was unrevealing, including genetic testing in 3. Paracetamol and ibuprofen were ineffective. Two children responded to gabapentin plus mexiletine, one to carbamazepine, two to mexiletine plus immunotherapy (methylprednisolone/IVIg). All recovered within 6 months, remaining well for years. These monophasic tempos and therapeutic responses are most consistent with acute post-infectious immune-mediated causality akin to Guillain-Barré large-fiber polyneuropathy. Skin biopsy and AFT for SFN, neuropathic-pain medications and immunotherapy should be considered for acute sporadic pediatric erythromelalgia.

Charcot-Marie-Tooth disease (CMT) is a hereditary sensory-motor neuropathy characterized by a strong clinical and genetic heterogeneity. Over the past few years, with the occurrence of whole-exome sequencing (WES) or whole-genome sequencing (WGS), the molecular diagnosis rate has been improved by allowing the screening of more than 80 genes at one time. In CMT, except the recurrent PMP22 duplication accounting for about 60% of pathogenic variations, pathogenic copy number variations (CNVs) are rarely reported and only a few studies screening specifically CNVs have been performed. The aim of the present study was to screen for CNVs in the most prevalent genes associated with CMT in a cohort of 200 patients negative for the PMP22 duplication. CNVs were screened using the Exome Depth software on next generation sequencing (NGS) data obtained by targeted capture and sequencing of a panel of 81 CMT associated genes. Deleterious CNVs were identified in four patients (2%), in four genes: GDAP1, LRSAM1, GAN, and FGD4. All CNVs were confirmed by high-resolution oligonucleotide array Comparative Genomic Hybridization (aCGH) and/or quantitative PCR. By identifying four new CNVs in four different genes, we demonstrate that, although they are rare mutational events in CMT, CNVs might contribute significantly to mutational spectrum of Charcot-Marie-Tooth disease and should be searched in routine NGS diagnosis. This strategy increases the molecular diagnosis rate of patients with neuropathy.

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiomyopathy, historically believed to affect 1 of 500 people. MYBPC3 pathogenic variations are the most frequent cause of familial HCM and more than 90% of them introduce a premature termination codon. The current study aims to determine the prevalence of deep intronic MYBPC3 pathogenic variations that could lead to splice mutations. To improve molecular diagnosis, a next-generation sequencing (NGS) workflow based on whole MYBPC3 sequencing of a cohort of 93 HCM patients, for whom no putatively causative point mutations were identified after NGS sequencing of a panel of 48 cardiomyopathy-causing genes, was performed. Our approach led us to reconsider the molecular diagnosis of six patients of the cohort (6.5%). These HCM probands were carriers of either a new large MYBPC3 rearrangement or splice intronic variations (five cases). Four pathogenic intronic variations, including three novel ones, were detected. Among them, the prevalence of one of them (NM_000256.3:c.1927+ 600 C>T) was estimated at about 0.35% by the screening of 1,040 unrelated HCM individuals. This study suggests that deep MYBPC3 splice mutations account for a significant proportion of HCM cases (6.5% of this cohort). Consequently, NGS sequencing of MYBPC3 intronic sequences have to be performed systematically.

International audience; 1 Facio-Scapulo Humeral dystrophy (FSHD) is the third most common myopathy, affecting 1 amongst 10,000 individuals (FSHD1, OMIM #158900). This autosomal dominant pathology is associated in 95% of cases with genetic and epigenetic alterations in the subtelomeric region at the extremity of the long arm of chromosome 4 (q arm). A large proportion of the remaining 5% of cases carry a mutation in the SMCHD1 gene (FSHD2, OMIM #158901). Here, we explored the 3D organization of the 4q35 locus by three-dimensions DNA in situ fluorescent hybridization (3D-FISH) in primary fibroblasts isolated from patients and healthy donors. We found that D4Z4 contractions and/or SMCHD1 mutations impact the spatial organization of the 4q35 region and trigger changes in the expression of different genes. Changes in gene expression were corroborated in muscle biopsies suggesting that the modified chromatin landscape impelled a modulation in the level of expression of a number of genes across the 4q35 locus in FSHD. Using induced pluripotent stem cells (hIPSC), we further examined whether chromatin organization is inherited after reprogramming or acquired during differentiation and showed that folding of the 4q35 region is modified upon differentiation. These results together with previous findings highlight the role of the D4Z4 macrosatellite repeat in the topological organization of chromatin and further indicate that the D4Z4-dependent 3D structure induces transcriptional changes of 4q35 genes expression.

International audience; Background Heritable forms of pulmonary arterial hypertension (PAH) and pulmonary veno-occlusive disease/pulmonary capillary haemangiomatosis (PVOD/PCH) diverge by lung histopathological lesions, clinical and para-clinical presentation, their responsible genes, and mode of transmission. Since the identification of the BMPR2 gene in families affected by PAH, mutations in several other genes have been discovered for both forms. The mutation landscape in these new genes is not yet well known.Methods We set up a next-generation sequencing-based targeted sequencing gene panel allowing known genes for PAH and PVOD/PCH to be analysed simultaneously. Genetic analysis was prospectively performed on 263 PAH and PVOD/PCH patients (adult and paediatric cases).Results Pathogenic mutations were identified in 19.5% of sporadic PAH patients (n=180), 54.5% of familial PAH patients and 13.3% of PVOD/PCH patients. BMPR2 was the most frequently mutated gene, followed by TBX4 in both paediatric and adult PAH. BMP9 mutations were identified in 1.2% of adult PAH cases. EIF2AK4 biallelic mutations were restricted to PVOD/PCH. A truncating mutation and a predicted loss-of-function variant were also identified in BMP10 in two severely affected sporadic PAH female patients.Conclusion Our results confirm that mutations are found in genes beyond BMPR2 in heritable PAH, emphasise the role of TBX4 and BMP9, and designate BMP10 as a new PAH gene.

International audience; Left ventricular non-compaction (LVNC) is a cardiomyopathy that may be of genetic origin; however, few data are available about the yield of mutation, the spectrum of genes and allelic variations. The aim of this study was to better characterize the genetic spectrum of isolated LVNC in a prospective cohort of 95 unrelated adult patients through the molecular investigation of 107 genes involved in cardiomyopathies and arrhythmias. Fifty-two pathogenic or probably pathogenic variants were identified in 40 patients (42%) including 31 patients (32.5%) with single variant and 9 patients with complex genotypes (9.5%). Mutated patients tended to have younger age at diagnosis than patients with no identified mutation. The most prevalent genes were TTN, then HCN4, MYH7, and RYR2. The distribution includes 13 genes previously reported in LVNC and 10 additional candidate genes. Our results show that LVNC is basically a genetic disease and support genetic counseling and cardiac screening in relatives. There is a large genetic heterogeneity, with predominant TTN null mutations and frequent complex genotypes. The gene spectrum is close to the one observed in dilated cardiomyopathy but with specific genes such as HCN4. We also identified new candidate genes that could be involved in this sub-phenotype of cardiomyopathy.

BackgroundSubtelomeres are variable regions between telomeres and chromosomal-specific regions. One of the most studied pathologies linked to subtelomeric imbalance is facioscapulohumeral dystrophy (FSHD). In most cases, this disease involves shortening of an array of D4Z4 macrosatellite elements at the 4q35 locus. The disease also segregates with a specific A-type haplotype containing a degenerated polyadenylation signal distal to the last repeat followed by a repetitive array of β-satellite elements. This classification applies to most patients with FSHD. A subset of patients called FSHD2 escapes this definition and carries a mutation in the SMCHD1 gene. We also recently described patients carrying a complex rearrangement consisting of a cis-duplication of the distal 4q35 locus identified by molecular combing.MethodsUsing this high-resolution technology, we further investigated the organisation of the 4q35 region linked to the disease and the 10q26 locus presenting with 98% of homology in controls and patients.ResultsOur analyses reveal a broad variability in size of the different elements composing these loci highlighting the complexity of these subtelomeres and the difficulty for genomic assembly. Out of the 1029 DNA samples analysed in our centre in the last 7 years, we also identified 54 cases clinically diagnosed with FSHD carrying complex genotypes. This includes mosaic patients, patients with deletions of the proximal 4q region and 23 cases with an atypical chromosome 10 pattern, infrequently found in the control population and never reported before.ConclusionOverall, this work underlines the complexity of these loci challenging the diagnosis and genetic counselling for this disease.

Background The etiological spectrum of hypertrophic cardiomypathies (HCM) is wide and some rare causes are largely underdiagnosed. Purpose Our aim is to assess the impact of the next generation sequencing (NGS) for the diagnosis of two rare genetic diseases: Fabry disease and hereditary transthyretin amyloidosis (GLA & TTR genes) in a population with HCM. Method We analysed 300 independent patients with HCM through a next generation sequencing (NGS) strategy using a panel of 107 genes involved in hereditary cardiomyopathies. The sequencing was performed by liquid-based capture of targeted areas (Nimblegen®) using HiSeq2500 device (Illumina®). The data were specifically reanalysed for this study, adjusting rules for pathogenicity interpretation based on ACMG guidelines and considering some high variant frequencies in these two genes. Results We studied 300 patients, 217 males & 83 females, mean age of 46 years. The NGS resulted in the identification of 266 variants (all classes included) in the 2 genes of interest (GLA: 189 variants, TTR: 77 variants). Further analysis led us to identify 4 causal mutations (pathogenic or probably pathogenic): 3 in GLA (p.Arg118Cys, p.Val269Ala, p.Ala143Thr) and one in TTR (p.Val142Ile). Fabry disease or amyloidosis were not diagnosed before NGS analysis. In the cohort, the prevalence was 1.3% for Fabry disease and 0.3% for ATTR. Conclusion NGS using a large panel is able to identify rare causes of HCM which were not previously suspected. The observed prevalences are comparable to those reported in the literature for the Fabry disease but are lower than those reported for the ATTR which could be due to the relatively young age of the patients in our analysed cohort. Our results support a systematic NGS screening with a large panel including GLA and TTR genes in patients referred for HCM. This screening is especially important as patients carrying Fabry or ATTR diseases may benefit from new specific therapies.

Ataxia-telangiectasia (A-T) is a recessive disorder caused by biallelic pathogenic variants of ataxia-telangiectasia mutated (ATM). This disease is characterized by progressive ataxia, telangiectasia, immune deficiency, predisposition to malignancies, and radiosensitivity. However, hypomorphic variants may be discovered associated with very atypical phenotypes, raising the importance of evaluating their pathogenic effects. In this study, multiple functional analyses were performed on lymphoblastoid cell lines from 36 patients, comprising 49 ATM variants, 24 being of uncertain significance. Thirteen patients with atypical phenotype and presumably hypomorphic variants were of particular interest to test strength of functional analyses and to highlight discrepancies with typical patients. Western-blot combined with transcript analyses allowed the identification of one missing variant, confirmed suspected splice defects and revealed unsuspected minor transcripts. Subcellular localization analyses confirmed the low level and abnormal cytoplasmic localization of ATM for most A-T cell lines. Interestingly, atypical patients had lower kinase defect and less altered cell-cycle distribution after genotoxic stress than typical patients. In conclusion, this study demonstrated the pathogenic effects of the 49 variants, highlighted the strength of KAP1 phosphorylation test for pathogenicity assessment and allowed the establishment of the Ataxia-TeLangiectasia Atypical Score to predict atypical phenotype. Altogether, we propose strategies for ATM variant detection and classification.

Background Hypertrophic cardiomyopathy (HCM) is a frequent hereditary cardiac disease and a major cause of sudden cardiac death (SCD). Although very useful, ESC risk score's predictive value has been interrogated since it was retrospective and did not include MRI parameters and new echocardiographic markers. Purpose To assess the additional value of new echocardiographic and MRI parameters in predicting SCD and outcome in patients with HCM. Methods Between 2007 and 2017, 307 patients with HCM were prospectively included and followed for 1.63 years. In addition to conventional prognostic factors, all patients underwent cardiac MRI evaluation of late gadolinium enhancement (LGE), and echocardiographic measurements of LV and LA volumes and strains, including left atrial peak longitudinal strain (PALS) and left atrial peak contraction strain (PACS). Primary end-point was SCD or appropriate defibrillator therapy. Secondary end-point was a composite end-point including death, hospitalization for heart failure, new-onset of atrial fibrillation, need for septal ablation, myomectomy, or heart transplantation. Results Among the 307 patients, 6 patients (2%) died and the secondary end-point occurred in 65 (21%). Factors associated with SCD by univariate analysis were low LVEF [HR 0.91 (0.93–0.99)] impaired PALS [HR 0.86 (0.72–0.97)], and moderate mitral regurgitation (MR). Factors associated with the secondary end-point were impaired LV GLS [HR 1.23 (1.13; 1.35)], impaired LA 4-chamber PALS [HR 0.94 (0.91; 0.97)] and PACS [HR 0.91 (0.86; 95)], LA 2 chamber PALS [HR 0.93 (0.89; 0.96)] and PACS [HR 0.86 (0.83;0. 94)], as well as TTE and MRI MR, and presence of MRI LGE. Impaired LA 4-chamber PALS remained as an independent predictor for the composite end-point [HR 0.92 (0.87; 0.97)] after adjustment. Conclusion This study suggests an additive prognostic value of an impaired LV and LA TTE strain, the presence of MR, and MRI LGE, to the classical ESC 7 recommended risk factors.

Objective Autosomal recessive spastic ataxia of Charlevoix–Saguenay (ARSACS) is caused by mutations in the SACS gene. SACS encodes sacsin, a protein whose function remains unknown, despite the description of numerous protein domains and the recent focus on its potential role in the regulation of mitochondrial physiology. This study aimed to identify new mutations in a large population of ataxic patients and to functionally analyze their cellular effects in the mitochondrial compartment. Methods A total of 321 index patients with spastic ataxia selected from the SPATAX network were analyzed by direct sequencing of the SACS gene, and 156 patients from the ATAXIC project presenting with congenital ataxia were investigated either by targeted or whole exome sequencing. For functional analyses, primary cultures of fibroblasts were obtained from 11 patients carrying either mono- or biallelic variants, including 1 case harboring a large deletion encompassing the entire SACS gene. Results We identified biallelic SACS variants in 33 patients from SPATAX, and in 5 nonprogressive ataxia patients from ATAXIC. Moreover, a drastic and recurrent alteration of the mitochondrial network was observed in 10 of the 11 patients tested. Interpretation Our results permit extension of the clinical and mutational spectrum of ARSACS patients. Moreover, we suggest that the observed mitochondrial network anomalies could be used as a trait biomarker for the diagnosis of ARSACS when SACS molecular results are difficult to interpret (ie, missense variants and heterozygous truncating variant). Based on our findings, we propose new diagnostic definitions for ARSACS using clinical, genetic, and cellular criteria. Ann Neurol 2015;78:871–886

International audience; Dilated cardiomyopathy (DCM) is one of the leading causes of heart failure with high morbidity and mortality. More than 40 genes have been reported to cause DCM. To provide new insights into the pathophysiology of dilated cardiomyopathy, a next-generation sequencing (NGS) workflow based on a panel of 48 cardiomyopathies-causing genes was used to analyze a cohort of 222 DCM patients. Truncating variants were detected on 63 unrelated DCM cases (28.4%). Most of them were identified, as expected, on TTN (29 DCM probands), but truncating variants were also identified on myofibrillar myopathies causing genes in 17 DCM patients (7.7% of the DCM cohort): 10 variations on FLNC and 7 variations on BAG3. This study confirms that truncating variants on myofibrillar myopathies causing genes are frequently associated with dilated cardiomyopathies and also suggest that FLNC mutations could be considered as a common cause of dilated cardiomyopathy. Molecular approaches that would allow to detect systematically truncating variants in FLNC and BAG3 into genetic testing should significantly increase test sensitivity, thereby allowing earlier diagnosis and therapeutic intervention for many patients with dilated cardiomyopathy.

Contains fulltext : 182328.pdf (Publisher’s version ) (Closed access) X-linked myotubular myopathy (XLMTM), a severe congenital myopathy, is caused by mutations in the MTM1 gene located on the X chromosome. A majority of affected males die in the early postnatal period, whereas female carriers are believed to be usually asymptomatic. Nevertheless, several affected females have been reported. To assess the phenotypic and pathological spectra of carrier females and to delineate diagnostic clues, we characterized 17 new unrelated affected females and performed a detailed comparison with previously reported cases at the clinical, muscle imaging, histological, ultrastructural and molecular levels. Taken together, the analysis of this large cohort of 43 cases highlights a wide spectrum of clinical severity ranging from severe neonatal and generalized weakness, similar to XLMTM male, to milder adult forms. Several females show a decline in respiratory function. Asymmetric weakness is a noteworthy frequent specific feature potentially correlated to an increased prevalence of highly skewed X inactivation. Asymmetry of growth was also noted. Other diagnostic clues include facial weakness, ptosis and ophthalmoplegia, skeletal and joint abnormalities, and histopathological signs that are hallmarks of centronuclear myopathy such as centralized nuclei and necklace fibers. The histopathological findings also demonstrate a general disorganization of muscle structure in addition to these specific hallmarks. Thus, MTM1 mutations in carrier females define a specific myopathy, which may be independent of the presence of an XLMTM male in the family. As several of the reported affected females carry large heterozygous MTM1 deletions not detectable by Sanger sequencing, and as milder phenotypes present as adult-onset limb-girdle myopathy, the prevalence of this myopathy is likely to be greatly underestimated. This report should aid diagnosis and thus the clinical management and genetic counseling of MTM1 carrier females. Furthermore, the clinical and pathological history of this cohort may be useful for therapeutic projects in males with XLMTM, as it illustrates the spectrum of possible evolution of the disease in patients surviving long term.

International audience; Background. - While it is known that 22q11.2 microdeletions (22q11.2-del) increase the risk of Parkinson's disease (PD), the characteristics of PD associated with 22q11.2-del have not been specifically explored.Objective. - This report aimed to assess the clinical characteristics and treatment responses of PD patients with 22q11.2-del, and to describe any features that might lead neurologists to investigate the comorbidity.Methods. - Nine PD patients (eight men, one woman) with 22q11.2-del were followed at seven centers of the French PD Expert Network (Ns-Park). Results. - PD diagnosis was made before 22q11.2-del diagnosis in seven cases; their main characteristics were early onset (32-48 years) and good initial levodopa sensitivity, but with a course characterized by severe and early-onset levodopa-induced motor complications and psychiatric manifestations. Three patients received deep brain stimulation (DBS) that was effective.Conclusion. - Searching for 22q11.2-del in PD patients presenting with suggestive features is relevant as the clinical presentation is similar to idiopathic PD, but with other associated characteristics, including a severe evolution. Results with DBS are similar to those reported for idiopathic PD.

Array comparative genomic hybridization (aCGH) has progressively replaced conventional karyotype in the diagnostic strategy of intellectual disability (ID) and congenital malformations. This technique increases not only the diagnostic rate but also the possibility of finding unexpected variants unrelated to the indication of referral, namely incidental findings. The incidental finding of copy number variants (CNVs) located in X-linked genes in girls addresses the crucial question of genetic counseling in the family. We report here five cases of CNVs involving the dystrophin gene detected by aCGH in girls referred for developmental delay, without any family history of dystrophinopathy. The rearrangements included three in-frame deletions; one maternally and two paternally inherited, and two frameshift duplications: one de novo and one from undetermined inheritance. In two cases, the deletion identified in a girl was transmitted by the asymptomatic father. In the case of the maternally inherited deletion, prenatal diagnosis of dystrophinopathy was proposed for an ongoing pregnancy, whereas the cause of developmental delay in the index case remained unknown. Through these cases, we discussed the challenges of genetic counseling in the family, regarding the predictive issues for male individuals at risk for a muscular dystrophy without precise knowledge of the clinical consequences of some CNVs in the DMD gene.

Background and objective Hypertrophic cardiomyopathy (HCM) is one of the leading causes of sudden cardiac death in young adults, with a prevalence of 1/500 in the general population. HCM is a genetic disease usually related to a sarcomeric gene mutation. Despite advances in knowledge, elucidation of the genetic cause is reached in only 30–60% of cases with conventional Sanger sequencing and analysis of a limited number of genes (usually the five major sarcomeric genes). We hypothesized that high-throughput sequencing of a large panel of genes will allow a more comprehensive evaluation of the etiologic spectrum of HCM. Methods and results We used high-throughput sequencing technology, with a panel of 107 genes (all the various cardiomyopathies and arrhythmia genes) that we recently developed (Nimblegen capture then Illumina MiSeq sequencing), in a cohort of 97 unrelated patients with HCM. We detected 2740 variants including 99 variants that we classified as pathogenic using restrictive criteria. A pathogenic mutation was identified (i) in 31 patients (32% of cohort of patients) in the group of 5 conventional sarcomeric genes (MYBPC3, MYH7, TNNT2, MYL2, TNNI3) including patients with multiple mutations, (ii) in 8 patients (8%) with a mutation in the group of additional sarcomeric genes (such as MYH6), (iii) in 4 patients (4%) with a mutation in the group of non-sarcomeric genes previously associated to HCM (such as GLA responsible for Fabry disease) and (iv) in additional patients with a mutation in new genes not yet reported in HCM (such as AKAP9). Conclusion High-throughput sequencing of a large panel of genes associated with hereditary heart diseases allowed us to determine the large genetic spectrum of HCM. We confirmed the prominent role of sarcomeric genes, highlighted the role of non-sarcomeric causes (some with specific therapeutics) and identified mutations in potential new genes responsible for the disease.

Introduction Left ventricular non-compaction (LVNC) is a rare cardiomyopathy that may be of genetic origin, however few data are available about the global yield of mutation screening, the spectrum of genes and allelic variations. Purpose The aim of this prospective study was to better characterize the allelic and genetic spectrum of isolated LVNC in a cohort of 95 unrelated adult patients through the molecular investigation of a custom panel of 107 genes involved in various cardiomyopathies and cardiac arrhythmias. Results Sixty pathogenic or probably pathogenic variants, including 47 novel ones, were identified in 44 patients (46.3%) including 31 patients (32.6%) with single variant and 13 patients with complex genotypes (13.6%). The most prevalent genes were TTN, then HCN4, MYH7, RYR2, MYH6, and MYBPC3. The genotype-phenotype correlation and the major clinical outcome enhanced the fact that mutated patients tended to have younger age of diagnosis. Interestingly the mutation yield was significantly higher in youngest patients 65 years (2/11, 18,2%, P = 0.02). The LV mean ejection fraction in patient with a mutation in sarcomeric genes was lower than in patients mutated in non-sarcomeric genes (41.7% vs. 52.7%, P = 0.05). The distribution includes 14 genes previously reported in LVNC and 13 additional candidate genes. Discussion Our results showed that LVNC is basically a genetic disease and support genetic counselling and cardiac screening in relatives. There is a large genetic heterogeneity, with predominant TTN mutations and a distribution close to the one observed in dilated cardiomyopathy but with specific genes such as HCN4. The prevalence of complex genotypes in these patients is important to notice in the context of genetic counselling. We also identified 13 potential new genes associated with LVNC.

Background and objectives: Hypertrophic cardiomyopathy (HCM) is expected to be caused by a heterozygous mutation in one of the 5 main sarcomere genes (MYBPC3, MYH7, TNNT2, MYL2, TNNI3). However, the routine diagnostic strategy consisting of the sequencing of these 5 genes allows identification of a mutation in only 50% of familial or sporadic cases, limiting accurate genetic counseling in families and predictive diagnosis in at-risk subjects. Purpose: We aimed at evaluating the value of Whole Exome Sequencing (WES), comparing its diagnostic yield with the routine diagnostic strategy, and clarifying the genetic spectrum of HCM. Methods: We performed WES in a large series of 200 new unrelated patients with primary HCM using the Agilent SureSelect V6 technology on Illumina Hiseq 2500. Patients were recruited between June 2015 and October 2016 in 5 French centers. In a first step of analysis, a panel of 145 genes involved in various hereditary cardiac diseases was searched for mutations. Bioinformatics analyses were performed in our lab. Only "certainly" (class 5) or "probably" pathogenic (class 4) mutations were considered, according to current guidelines Results: A total of 565 filtered variants predicted as pathogenic in 111 genes were retained after bioinformatics analysis, literature and databases review. The main results are the following:-A mutation in 1 of the 5 main sarcomere genes was observed in only 72 (36%) patients, with no mutation on the TNNI3 gene.-Conversely, 495 other pathogenic mutations were identified in 185 patients, giving a total 92.5% detection rate of at least one pathogenic gene mutation. Among them, the most prevalent mutated genes were FLNC, LDB3, MYPN, ANK2, RYR2 and NEBL. In addition, unexpected diagnosis of treatable affections such as Fabry disease (n=1) and TTR amyloidosis (n=1) were identified by WES analysis-A single mutation was identified in only 27 patients (13.5% of cases). In 158 patients (79%), multiple variants were identified with 2 to 8 mutations per patient.-Finally, in only 15 patients (7.5%), no mutation was identified in this panel of 145 genes. Conclusions: 1. Exome sequencing improves the diagnostic output in HCM with 92.5% of patients carrying at least one pathogenic mutation in a panel of 145 genes involved in various hereditary cardiac diseases 2. Genetic heterogeneity is much larger than expected with multiple variants in sarcomere genes, but also non-sarcomere, and ion channel genes unexpected in HCM. 3. Early unexpected diagnosis of Fabry disease or TTR amyloidosis can be obtained by our strategy of one-step large genetic analysis. 4. Our results suggest that the commonly accepted monogenic model of HCM involving one mutation in one gene is not the major mechanism in HCM. Rather, oligogenism with 1 major and several minor variants is our proposed new pathogenic mechanism in HCM.