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PURPOSE: Moyamoya angiopathy (MMA) is a cerebrovascular disease characterized by occlusion of large arteries, which leads to strokes starting in childhood. Twelve altered genes predispose to MMA but the majority of cases of European descent do not have an identified genetic trigger. METHODS: Exome sequencing from 39 trios were analyzed. RESULTS: We identified four de novo variants in three genes not previously associated with MMA: CHD4, CNOT3, and SETD5. Identification of additional rare variants in these genes in 158 unrelated MMA probands provided further support that rare pathogenic variants in CHD4 and CNOT3 predispose to MMA. Previous studies identified de novo variants in these genes in children with developmental disorders (DD), intellectual disability, and congenital heart disease. CONCLUSION: These genes encode proteins involved in chromatin remodeling, and taken together with previously reported genes leading to MMA-like cerebrovascular occlusive disease (YY1AP1, SMARCAL1), implicate disrupted chromatin remodeling as a molecular pathway predisposing to early onset, large artery occlusive cerebrovascular disease. Furthermore, these data expand the spectrum of phenotypic pleiotropy due to alterations of CHD4, CNOT3, and SETD5 beyond DD to later onset disease in the cerebrovascular arteries and emphasize the need to assess clinical complications into adulthood for genes associated with DD.

Dissections or ruptures of aortic aneurysms remain a leading cause of death in the developed world, with the majority of deaths being preventable if individuals at risk are identified and properly managed. Genetic variants predispose individuals to these aortic diseases. In the case of thoracic aortic aneurysm and dissections (thoracic aortic disease), genetic data can be used to identify some at-risk individuals and dictate management of the associated vascular disease. For abdominal aortic aneurysms, genetic associations have been identified, which provide insight on the molecular pathogenesis but cannot be used clinically yet to identify individuals at risk for abdominal aortic aneurysms. This compendium will discuss our current understanding of the genetic basis of thoracic aortic disease and abdominal aortic aneurysm disease. Although both diseases share several pathogenic similarities, including proteolytic elastic tissue degeneration and smooth muscle dysfunction, they also have several distinct differences, including population prevalence and modes of inheritance.

Importance Moyamoya disease (MMD), a progressive vasculopathy leading to narrowing and ultimate occlusion of the intracranial internal carotid arteries, is a cause of childhood stroke. The cause of MMD is poorly understood, but genetic factors play a role. Several familial forms of MMD have been identified, but the cause of most cases remains elusive, especially among non-East Asian individuals. Objective To assess whether ultrarare de novo and rare, damaging transmitted variants with large effect sizes are associated with MMD risk. Design, setting, and participants A genetic association study was conducted using whole-exome sequencing case-parent MMD trios in a small discovery cohort collected over 3.5 years (2016-2019); data were analyzed in 2020. Medical records from US hospitals spanning a range of 1 month to 1.5 years were reviewed for phenotyping. Exomes from a larger validation cohort were analyzed to identify additional rare, large-effect variants in the top candidate gene. Participants included patients with MMD and, when available, their parents. All participants who met criteria and were presented with the option to join the study agreed to do so; none were excluded. Twenty-four probands (22 trios and 2 singletons) composed the discovery cohort, and 84 probands (29 trios and 55 singletons) composed the validation cohort. Main outcomes and measures Gene variants were identified and filtered using stringent criteria. Enrichment and case-control tests assessed gene-level variant burden. In silico modeling estimated the probability of variant association with protein structure. Integrative genomics assessed expression patterns of MMD risk genes derived from single-cell RNA sequencing data of human and mouse brain tissue. Results Of the 24 patients in the discovery cohort, 14 (58.3%) were men and 18 (75.0%) were of European ancestry. Three of 24 discovery cohort probands contained 2 do novo (1-tailed Poisson P = 1.1 × 10-6) and 1 rare, transmitted damaging variant (12.5% of cases) in DIAPH1 (mammalian diaphanous-1), a key regulator of actin remodeling in vascular cells and platelets. Four additional ultrarare damaging heterozygous DIAPH1 variants (3 unphased) were identified in 3 other patients in an 84-proband validation cohort (73.8% female, 77.4% European). All 6 patients were non-East Asian. Compound heterozygous variants were identified in ena/vasodilator-stimulated phosphoproteinlike protein EVL, a mammalian diaphanous-1 interactor that regulates actin polymerization. DIAPH1 and EVL mutant probands had severe, bilateral MMD associated with transfusion-dependent thrombocytopenia. DIAPH1 and other MMD risk genes are enriched in mural cells of midgestational human brain. The DIAPH1 coexpression network converges in vascular cell actin cytoskeleton regulatory pathways. Conclusions and relevance These findings provide the largest collection to date of non-East Asian individuals with sporadic MMD harboring pathogenic variants in the same gene. The results suggest that DIAPH1 is a novel MMD risk gene and impaired vascular cell actin remodeling in MMD pathogenesis, with diagnostic and therapeutic ramifications.

Genetic variation plays a significant role in predisposing individuals to thoracic aortic aneurysms and dissections. Advances in genomic research have led to the discovery of 11 genes validated to cause heritable thoracic aortic disease (HTAD). Identifying the pathogenic variants responsible for aortic disease in affected patients confers substantial clinical utility by establishing a definitive diagnosis to inform tailored treatment and management, and enables identification of at-risk relatives to prevent downstream morbidity and mortality. The availability and access to clinical genetic testing has improved dramatically such that genetic testing is considered an integral part of the clinical evaluation for patients with thoracic aortic disease. This review provides an update on our current understanding of the genetic basis of thoracic aortic disease, practical recommendations for genetic testing, and clinical implications.

ObjectiveTo test the hypothesis that de novo genetic variants are responsible for moyamoya disease (MMD) in children with unaffected relatives, we performed exome sequencing of 28 affected children and their unaffected parents.MethodsExome sequencing was performed on 28 trios of affected patients with MMD and unaffected parents.ResultsWe identified 3 novel rare de novo RNF213 variants, 1 in the RING domain and 2 in a highly conserved region distal to the RING domain (4,114–4,120). These de novo cases of MMD present at a young age with aggressive MMD and uniquely have additional occlusive vascular lesions, including renal artery stenosis. Two previously reported cases had de novo variants in the same limited region and presented young with aggressive MMD, and 1 case had narrowing of the inferior abdominal aorta.ConclusionsThese results indicate a novel syndrome associated with RNF213 rare variants defined by de novo mutations disrupting highly conserved amino acids in the RING domain and a discrete region distal to the RING domain delimited by amino acids 4,114 to 4,120 leading to onset of severe MMD before 3 years of age and occlusion of other arteries, including the abdominal aorta, renal, iliac, and femoral arteries.

BACKGROUND Bicuspid aortic valve (BAV) is the most common cardiovascular malformation in adults, with a prevalence of 0.5%-2%. The prevalence of BAV in cohorts who were ascertained due to thoracic aortic aneurysms or acute aortic dissections (TAD) is as high as 20%. However, the contribution of causal BAV genes to TAD is not known. Therefore, we evaluated rare deleterious variants of GATA4, NOTCH1, SMAD6, or ROBO4 in patients with BAV who presented with TAD. METHODS Our cohort consisted of 487 probands with Heritable Thoracic Aortic Aneurysms or Dissections (HTAD, 12% BAV, 29% female) and 63 probands with Early onset complications of Bicuspid Aortic Valve disease (EBAV, 63% TAD, 34% female). After whole exome sequencing, we functionally annotated GATA4, NOTCH1, SMAD6, and ROBO4 variants and compared the prevalence of rare variants in these genes to controls without HTAD. RESULTS We identified 11 rare deleterious variants of GATA4, SMAD6, or ROBO4 in 12 (18%) EBAV cases. The burden of rare SMAD6 and GATA4 variants was significantly enriched in EBAV but not in HTAD cases, even among HTAD cases with BAV (p

Introduction: Moyamoya disease (MMD) is a cerebrovascular disease often causing pediatric onset strokes and characterized by progressive bilateral occlusion of the distal internal carotid arteries and formation of a compensatory network of collateral vessels. Several genes harbor variants that increase the risk for MMD, but the majority of cases of European descent does not have an identified genetic cause. Hypothesis: MMD is associated with significant genetic heterogeneity, i.e., many genes in the human genome can be altered to predispose to this condition. Methods: To identify novel genes for MMD, exome sequencing was performed on DNA from 145 individuals from 80 families with one or more affected members. Bioinformatics filtering included a CADD (GRCh37-v1.4) score > 20 and a minor allele frequency < 0.0001 in gnomAD (v2.1.1 controls). For a subset of ANO1 mutant alleles, we characterized the channel activities via patch recording and assessed protein localization in heterologous cell cultures. Results: We identified 6 rare variants in ANO1 ( TMEM16A ), which encodes an evolutionarily conserved calcium-activated chloride channel. One rare heterozygous variant, p.Met658Val (CADD: 22.9, absent in gnomAD), was found in two very distantly related MMD families and segregated with disease in multiple affected members; p.Glu459Lys and p.Arg890Gln were identified in two unrelated affected probands. Through Matchmaker Exchange (MyGene2) collaboration, we identified 3 additional rare variants: homozygous p.Glu170Lys in a consanguineous MMD family, heterozygous p.Thr740Ile in a MMD case and p.Ala333Ser in a case with ischemic stroke. Functional analyses determined that p.Glu170Lys affects channel gating and calcium sensitivity, producing much smaller chloride current, but the channel itself is more sensitive to calcium, which means it is more likely to open. Ano1 knock out (KO) in mice is lethal by 1 week of age with pathology in multiple organ systems. Smooth muscle cells-specific KO is not lethal, and phenotyping of these mice is ongoing. Conclusions: ANO1 is a novel gene predisposing to MMD and future studies will focus on defining the role of ANO1 protein to connect the altered gene to the occlusive lesions observed in MMD patients.

International audience; Ventricular septal defect (VSD) including outlet VSD of double outlet right ventricle (DORV) and perimembranous VSD are among the most common congenital heart diseases found at birth. HOXB1 encodes a homeodomain transcription factor essential for normal cardiac outflow tract development. The aim of the present study was to investigate the possible genetic effect of sequence variations in HOXB1 on VSD. The coding regions and splice junctions of the HOXB1 gene were sequenced in 57 unrelated VSD patients. As a result, a homozygous c.74\₈2dup (p.Pro28delinsHisSerAlaPro) variant was identified in one individual with DORV. We also identified five previously reported polymorphisms (rs35114525, rs12946855, rs14534040, rs12939811, and rs7207109) in 18 patients (12 DORV and 6 perimembranous VSD). Our study did not show any pathogenic alterations in the coding region of HOXB1 among patients with VSD. To our knowledge this is the first study investigating the role of HOXB1 in nonsyndromic VSD, which provide more insight on the etiology of this disease.

Aims-During embryogenesis, the onset of circulatory blood flow generates a variety of hemodynamic forces which reciprocally induce changes in cardiovascular development and performance. It has been known for some time that these forces can be detected by as yet unknown mechanosensory systems which in turn promote cardiogenic events such as outflow tract and aortic valve development. PIEZO1 is a mechanosensitive ion channel present in endothelial cells where it serves to detect hemodynamic forces making it an ideal candidate to play a role during cardiac development. We sought to determine whether PIEZO1 is required for outflow tract and aortic valve development.Methods and results-By analysing heart development in zebrafish we have determined thatpiezo1is expressed in the developing outflow tract where it serves to detect hemodynamic forces. In particular, we have found that mechanical forces generated during the cardiac cycle activate Piezo1 which triggers nitric oxide to be released in the outflow tract. Consequently, disrupting Piezo1 signalling leads to defective outflow tract and aortic valve development and indicates this gene may be involved in the etiology of congenital heart diseases. Based on these findings, we analysed genomic data generated from a cohort of bicuspid aortic valve patients and identified 3 probands who each harboured a novel variant inPIEZO1. Subsequentin vitroandin vivoassays indicates that these variants behave as dominant negatives leading to an inhibition of normal PIEZO1 mechanosensory activity and defective aortic valve development.Conclusion-These data indicate that the mechanosensitive ion channelpiezo1is required for OFT and aortic valve development and, furthermore, dominant negative variants ofPIEZO1appear to be associated with BAV in humans.

Notice à reprendre en chantier qualité avec la version finale de l’Editeur; International audience; We identified, through a genome-wide search for new imprinted genes in the human placenta, DSCAM (Down Syndrome Cellular Adhesion Molecule) as a paternally expressed imprinted gene. Our work revealed the presence of a Differentially Methylated Region (DMR), located within intron 1 that might regulate the imprinting in the region. This DMR showed a maternal allele methylation, compatible with its paternal expression. We showed that DSCAM is present in endothelial cells and the syncytiotrophoblast layer of the human placenta. In mouse, Dscam expression is biallelic in foetal brain and placenta excluding any possible imprinting in these tissues. This gene encodes a cellular adhesion molecule mainly known for its role in neurone development but its function in the placenta remains unclear. We report here the first imprinted gene located on human chromosome 21 with potential clinical implications.

The major diseases affecting the thoracic aorta are aneurysms and acute dissections, and pathogenic variants in 11 genes are confirmed to lead to heritable thoracic aortic disease. However, many families in which multiple members have thoracic aortic disease do not have alterations in the known aortopathy genes. Genes highly expressed in the aorta were assessed for rare variants in exome sequencing data from such families, and compound rare heterozygous variants (p.Pro45Argfs∗25 and p.Glu750∗) in LTBP3 were identified in affected members of one family. A homozygous variant (p.Asn678_Gly681delinsThrCys) that introduces an additional cysteine into an epidermal growth factor (EGF)-like domain in the corresponding protein, latent TGF-β binding protein (LTBP-3), was identified in a second family. Individuals with compound heterozygous or homozygous variants in these families have aneurysms and dissections of the thoracic aorta, as well as aneurysms of the abdominal aorta and other arteries, along with dental abnormalities and short stature. Heterozygous carriers of the p.Asn678_Gly681delinsThrCys variant have later onset of thoracic aortic disease, as well as dental abnormalities. In these families, LTBP3 variants segregated with thoracic aortic disease with a combined LOD score of 3.9. Additionally, heterozygous rare LTBP3 variants were found in individuals with early onset of acute aortic dissections, and some of these variants disrupted LTBP-3 levels or EGF-like domains. When compared to wild-type mice, Ltbp3−/− mice have enlarged aortic roots and ascending aortas. In summary, homozygous LTBP3 pathogenic variants predispose individuals to thoracic aortic aneurysms and dissections, along with the previously described skeletal and dental abnormalities.

Inherited ectopia lentis (EL) is most commonly caused by Marfan syndrome (MFS), a multisystemic disorder caused by mutations in FBN1. Historically the diagnosis for patients with EL who have no systemic features of MFS is isolated EL (IEL). However, the Ghent nosology for MFS was updated in 2010 and made some important alterations. In particular, patients with EL and a FBN1 mutation are now categorically diagnosed with MFS, if their mutation has previously been described with aortic dilation/dissection. This carries significant systemic implications, as many patients previously diagnosed with IEL are now reclassified. We provide a review of all published cases of IEL caused by FBN1 mutations over the last 20 years to assess what impact the new Ghent nosology has on these. Indeed, 57/123 probands (46.3%) are now classified as MFS according to the revised Ghent nosology and 37/96 mutations (38.5%) reported to cause isolated EL have also been found in patients with aortic dilation/dissection. These findings suggest that EL caused by mutations in FBN1 is actually part of a spectrum of fibrillinopathies with MFS, and the term 'IEL' should be avoided in such cases.

International audience; Adoption of next-generation sequencing (NGS) in a diagnostic context raises numerous questions with regard to identification and reports of secondary variants (SVs) in actionable genes. To better understand the whys and wherefores of these questioning, it is necessary to understand how they are selected during the filtering process and how their proportion can be estimated. It is likely that SVs are underestimated and that our capacity to label all true SVs can be improved. In this context, Locus-specific databases (LSDBs) can be key by providing a wealth of information and enabling classifying variants. We illustrate this issue by analyzing 318 SVs in 23 actionable genes involved in cancer susceptibility syndromes identified through sequencing of 572 participants selected for a range of atherosclerosis phenotypes. Among these 318 SVs, only 43.4% are reported in Human Gene Mutation Database (HGMD) Professional versus 71.4% in LSDB. In addition, 23.9% of HGMD Professional variants are reported as pathogenic versus 4.8% for LSDB. These data underline the benefits of LSDBs to annotate SVs and minimize overinterpretation of mutations thanks to their efficient curation process and collection of unpublished data. (C) 2016 Wiley Periodicals, Inc.

International audience; Whole-exome sequencing (WES) is increasingly applied to research and clinical diagnosis of human diseases. It typically results in large amounts of genetic variations. Depending on the mode of inheritance, only one or two correspond to pathogenic mutations responsible for the disease and present in affected individuals. Therefore , it is crucial to filter out nonpathogenic variants and limit downstream analysis to a handful of candidate mutations. We have developed a new computational combi-natorial system UMD-Predictor (http://umd-predictor.eu) to efficiently annotate cDNA substitutions of all human transcripts for their potential pathogenicity. It combines biochemical properties, impact on splicing signals, localiza-tion in protein domains, variation frequency in the global population, and conservation through the BLOSUM62 global substitution matrix and a protein-specific conservation among 100 species. We compared its accuracy with the seven most used and reliable prediction tools, using the largest reference variation datasets including more than 140,000 annotated variations. This system consistently demonstrated a better accuracy, specificity, Matthews correlation coefficient, diagnostic odds ratio, speed, and provided the shortest list of candidate mutations for WES. Webservices allow its implementation in any bioinfor-matics pipeline for next-generation sequencing analysis. It could benefit to a wide range of users and applications varying from gene discovery to clinical diagnosis.

International audience; Congenital tricuspid valve disease is a rare defect that includes regurgitation, stenosis and Ebstein's anomaly. We report a case of severe tricuspid regurgitation associated with functional mitral regurgitation in a 47-year-old man with congestive heart failure. Transthoracic echocardiography (TTE) ruled out any Ebstein's anomaly. Three-dimensional TTE revealed a `tricuspid hole' into the anterior leaflet that was only attached to the tricuspid annulus next to both anteroseptal and anteroposterior commissures. There was no sign of leaflet tear or perforation. The surgical repair of the tricuspid and mitral valves was performed with an optimal result. No sign of endocarditis or rheumatic disease was observed during the intervention. Sequence analysis of GATA4, HEY2 and ZFPM2 genes was performed, but no causative mutation was identified.

International audience; High-throughput next-generation sequencing such as whole-exome and whole-genome sequencing are being rapidly integrated into clinical practice. The use of these techniques leads to the identification of secondary variants for which decisions about the reporting or not to the patient need to be made. The American College of Medical Genetics and Genomics recently published recommendations for the reporting of these variants in clinical practice for 56 "actionable" genes. Among these, seven are involved in Marfan Syndrome And Related Disorders (MSARD) resulting from mutations of the FBN1, TGFBR1 and 2, ACTA2, SMAD3, MYH11 and MYLK genes. Here, we show that mutations collected in UMD databases for MSARD genes (UMD-MSARD) are rarely reported, including the most frequent ones, in global scale initiatives for variant annotation such as the NHLBI GO Exome Sequencing Project (ESP), the Exome Aggregation Consortium (ExAC), and ClinVar. The predicted pathogenic mutations reported in global scale initiatives but absent in locus-specific databases (LSDBs) mainly correspond to rare events. UMD-MSARD databases are therefore the only resources providing access to the full spectrum of known pathogenic mutations. They are the most comprehensive resources for clinicians and geneticists to interpret MSARD-related variations not only primary variants but also secondary variants.

BACKGROUND: Candida glabrata follows C. albicans as the second or third most prevalent cause of candidemia worldwide. These two pathogenic yeasts are distantly related, C. glabrata being part of the Nakaseomyces, a group more closely related to Saccharomyces cerevisiae. Although C. glabrata was thought to be the only pathogenic Nakaseomyces, two new pathogens have recently been described within this group: C. nivariensis and C. bracarensis. To gain insight into the genomic changes underlying the emergence of virulence, we sequenced the genomes of these two, and three other non-pathogenic Nakaseomyces, and compared them to other sequenced yeasts. RESULTS: Our results indicate that the two new pathogens are more closely related to the non-pathogenic N. delphensis than to C. glabrata. We uncover duplications and accelerated evolution that specifically affected genes in the lineage preceding the group containing N. delphensis and the three pathogens, which may provide clues to the higher propensity of this group to infect humans. Finally, the number of Epa-like adhesins is specifically enriched in the pathogens, particularly in C. glabrata. CONCLUSIONS: Remarkably, some features thought to be the result of adaptation of C. glabrata to a pathogenic lifestyle, are present throughout the Nakaseomyces, indicating these are rather ancient adaptations to other environments. Phylogeny suggests that human pathogenesis evolved several times, independently within the clade. The expansion of the EPA gene family in pathogens establishes an evolutionary link between adhesion and virulence phenotypes. Our analyses thus shed light onto the relationships between virulence and the recent genomic changes that occurred within the Nakaseomyces. This work was supported by funding from the European Research Council/nunder the European Union’s Seventh Framework Programme (FP/2007- 2013)/ERC Grant Agreement n.310325, a Grant from the Qatar National Research Fund grant (NPRP 5-298-3-086), and by a grant from the Spanish Ministry of Economy and Competitiveness (BIO2012-37161). CF’s research is/nfunded in part by an “Attractivité” grant from the University Paris Sud. GA is/na recipient of a Marie Curie grant (FP7-PEOPLE-2010-IEF-No.274223). SB, HD and RA are recipients of, respectively, a shared post-doctoral grant and a Ph. D. grant, from the Région Ile-de-France’s DIM Malinf program. JAC was supported by the Ph.D. Program in Computational Biology of the Instituto Gulbenkian de Ciência, Portugal (sponsored by Fundação Calouste Gulbenkian, Siemens SA, and Fundação para a Ciência e Tecnologia; SFRH/BD/33528/2008)

Supplemental materials : www.landesbioscience.com/journals/epigenetics/article/21495; Genomic imprinting characterizes genes with a monoallelic expression, which is dependent on the parental origin of each allele. Approximately 150 imprinted genes are known to date, in humans and mice but, though computational searches have tried to extract intrinsic characteristics of these genes to identify new ones, the existing list is probably far from being comprehensive. We used a high-throughput strategy by diverting the classical use of genotyping microarrays to compare the genotypes of mRNA/cDNA vs. genomic DNA to identify new genes presenting monoallelic expression, starting from human placental material. After filtering of data, we obtained a list of 1,082 putative candidate monoallelic SNPs located in more than one hundred candidate genes. Among these, we found known imprinted genes, such as IPW, GRB10, INPP5F and ZNF597, which contribute to validate the approach. We also explored some likely candidates of our list and identified seven new imprinted genes, including ZFAT, ZFAT-AS1, GLIS3, NTM, MAGI2, ZC3H12Cand LIN28B, four of which encode zinc finger transcription factors. They are, however, not imprinted in the mouse placenta, except for Magi2. We analyzed in more details the ZFAT gene, which is paternally expressed in the placenta (as ZFAT-AS1, a non-coding antisense RNA) but biallelic in other tissues. The ZFAT protein is expressed in endothelial cells, as well as in syncytiotrophoblasts. The expression of this gene is, moreover, downregulated in placentas from complicated pregnancies. With this work we increase by about 10% the number of known imprinted genes in humans.

L’empreinte parentale est un phenomene epigenetique complexe qui regule l’expression monoallelique de certains genes en fonction de l’origine parentale de l’allele. Les genes soumis a empreinte (GSE) participent au developpement placentaire et fœtal. Des defauts d’empreinte de certains GSE entrainent des syndromes cliniques associant une pathologie placentaire a l’origine notamment d’un defaut de croissance fœtale, et des manifestations neuro-developpementales. Environ 70 GSE ont ete identifies a ce jour chez l’homme. Nous avons developpe une strategie de criblage haut debit pour identifier de nouveaux GSE dans le placenta humain. Une premiere serie de validation a permis de confirmer le statut d’empreinte d’une dizaine de nouveaux genes [1] . Recemment, nous avons revele le statut de GSE pour le gene DSCAM (Down Syndrome Cellular Adhesion Molecule). Ce gene, qui se trouve dans la region critique du syndrome de Down, est ainsi le premier GSE identifie sur le chromosome 21. Notre etude montre que c’est l’allele paternel qui est exprime dans le placenta. Des resultats preliminaires nous laissent penser que l’empreinte de ce gene pourrait etre regulee par une region differentiellement methylee en amont du gene. L’etude par immunohistochimie de coupes placentaires montre une expression dans les cellules endotheliales et le syncytiotrophoblaste pouvant suggerer un role dans l’angiogenese placentaire via son ligand Netrin. Une etude est en cours a partir d’un modele cellulaire de trophoblaste avant et apres syncytialisation pour analyser son role dans ce type cellulaire. Par ailleurs, DSCAM est connu pour son role dans la mise en place des connections inter-neurones [2] . Une etude est en cours sur des modeles murins afin d’analyser le statut d’empreinte de ce gene dans le tissu nerveux et les consequences d’un defaut d’expression de son ligand Netrin sur le developpement placentaire.