Willems M

References (2)

Title : Efficient strategy for the molecular diagnosis of intellectual disability using targeted high-throughput sequencing - Redin_2014_J.Med.Genet_51_724
Author(s) : Redin C , Gerard B , Lauer J , Herenger Y , Muller J , Quartier A , Masurel-Paulet A , Willems M , Lesca G , El-Chehadeh S , Le Gras S , Vicaire S , Philipps M , Dumas M , Geoffroy V , Feger C , Haumesser N , Alembik Y , Barth M , Bonneau D , Colin E , Dollfus H , Doray B , Delrue MA , Drouin-Garraud V , Flori E , Fradin M , Francannet C , Goldenberg A , Lumbroso S , Mathieu-Dramard M , Martin-Coignard D , Lacombe D , Morin G , Polge A , Sukno S , Thauvin-Robinet C , Thevenon J , Doco-Fenzy M , Genevieve D , Sarda P , Edery P , Isidor B , Jost B , Olivier-Faivre L , Mandel JL , Piton A
Ref : Journal of Medical Genetics , 51 :724 , 2014
Abstract : BACKGROUND: Intellectual disability (ID) is characterised by an extreme genetic heterogeneity. Several hundred genes have been associated to monogenic forms of ID, considerably complicating molecular diagnostics. Trio-exome sequencing was recently proposed as a diagnostic approach, yet remains costly for a general implementation. METHODS: We report the alternative strategy of targeted high-throughput sequencing of 217 genes in which mutations had been reported in patients with ID or autism as the major clinical concern. We analysed 106 patients with ID of unknown aetiology following array-CGH analysis and other genetic investigations. Ninety per cent of these patients were males, and 75% sporadic cases. RESULTS: We identified 26 causative mutations: 16 in X-linked genes (ATRX, CUL4B, DMD, FMR1, HCFC1, IL1RAPL1, IQSEC2, KDM5C, MAOA, MECP2, SLC9A6, SLC16A2, PHF8) and 10 de novo in autosomal-dominant genes (DYRK1A, GRIN1, MED13L, TCF4, RAI1, SHANK3, SLC2A1, SYNGAP1). We also detected four possibly causative mutations (eg, in NLGN3) requiring further investigations. We present detailed reasoning for assigning causality for each mutation, and associated patients' clinical information. Some genes were hit more than once in our cohort, suggesting they correspond to more frequent ID-associated conditions (KDM5C, MECP2, DYRK1A, TCF4). We highlight some unexpected genotype to phenotype correlations, with causative mutations being identified in genes associated to defined syndromes in patients deviating from the classic phenotype (DMD, TCF4, MECP2). We also bring additional supportive (HCFC1, MED13L) or unsupportive (SHROOM4, SRPX2) evidences for the implication of previous candidate genes or mutations in cognitive disorders. CONCLUSIONS: With a diagnostic yield of 25% targeted sequencing appears relevant as a first intention test for the diagnosis of ID, but importantly will also contribute to a better understanding regarding the specific contribution of the many genes implicated in ID and autism.
ESTHER : Redin_2014_J.Med.Genet_51_724
PubMedSearch : Redin_2014_J.Med.Genet_51_724
PubMedID: 25167861
Gene_locus related to this paper: human-NLGN3

Title : Characterization of the stem cell system of the acoel Isodiametra pulchra - De Mulder_2009_BMC.Dev.Biol_9_69
Author(s) : De Mulder K , Kuales G , Pfister D , Willems M , Egger B , Salvenmoser W , Thaler M , Gorny AK , Hrouda M , Borgonie G , Ladurner P
Ref : BMC Developmental Biology , 9 :69 , 2009
Abstract : BACKGROUND: Tissue plasticity and a substantial regeneration capacity based on stem cells are the hallmark of several invertebrate groups such as sponges, cnidarians and Platyhelminthes. Traditionally, Acoela were seen as an early branching clade within the Platyhelminthes, but became recently positioned at the base of the Bilateria. However, little is known on how the stem cell system in this new phylum is organized. In this study, we wanted to examine if Acoela possess a neoblast-like stem cell system that is responsible for development, growth, homeostasis and regeneration.
RESULTS: We established enduring laboratory cultures of the acoel Isodiametra pulchra (Acoela, Acoelomorpha) and implemented in situ hybridization and RNA interference (RNAi) for this species. We used BrdU labelling, morphology, ultrastructure and molecular tools to illuminate the morphology, distribution and plasticity of acoel stem cells under different developmental conditions. We demonstrate that neoblasts are the only proliferating cells which are solely mesodermally located within the organism. By means of in situ hybridisation and protein localisation we could demonstrate that the piwi-like gene ipiwi1 is expressed in testes, ovaries as well as in a subpopulation of somatic stem cells. In addition, we show that germ cell progenitors are present in freshly hatched worms, suggesting an embryonic formation of the germline. We identified a potent stem cell system that is responsible for development, homeostasis, regeneration and regrowth upon starvation.
CONCLUSIONS: We introduce the acoel Isodiametra pulchra as potential new model organism, suitable to address developmental questions in this understudied phylum. We show that neoblasts in I. pulchra are crucial for tissue homeostasis, development and regeneration. Notably, epidermal cells were found to be renewed exclusively from parenchymally located stem cells, a situation known only from rhabditophoran flatworms so far. For further comparison, it will be important to analyse the stem cell systems of other key-positioned understudied taxa.
ESTHER : De Mulder_2009_BMC.Dev.Biol_9_69
PubMedSearch : De Mulder_2009_BMC.Dev.Biol_9_69
PubMedID: 20017953