The prevalence of Autism Spectrum Disorder (ASD) and its defining features has been increasingly investigated in genetic syndromes associated with intellectual disability, with syndrome specific profiles reported. The experience of catatonia and other movement disorders in people with ASD has been increasing highlighted within both research and diagnostic guidelines. However, these issues have not typically been investigated alongside other features of ASD within research into genetic syndromes. The first paper in this thesis provides a review of the literature on movement disorders in genetic syndromes associated with ASD, which focuses on the prevalence of reported movement disorders, the methods of assessment used, and the quality of research to date. An empirical study is reported in Paper 2. Within a cohort of individuals with Cornelia de Lange and Fragile X syndromes the prevalence of attenuated behaviour [autistic catatonia] is examined, based on parent/carer report, and the extent to which features of ASD predict later attenuated behaviour is investigated. Paper 3 provides a critical reflection on the first two papers as well as some wider considerations on undertaking research in this area. The results of both the literature review and the empirical study indicated that across a number of genetic syndromes (Angelman syndrome, Cornelia de Lange syndrome, Fragile X syndrome and Rett syndrome) attenuated behaviour [autistic catatonia] and/or movement disorders affect a substantial proportion of individuals. Furthermore, repetitive behaviours, one of the characteristic features of ASD, appear to predict later attenuated behaviour in Cornelia de Lange and Fragile X syndromesThe results presented in this thesis have important implications for the way services support individuals with specific genetic syndromes. Paper 1 confirms the high prevalence of movement problems in Angelman and Rett syndromes, and Paper 2 provides a new insight into movement problems in Cornelia de Lange and Fragile X syndromes. Movement disorders are reported to impact negatively on wellbeing and quality of life in people with ASD, and are likely to have a similar impact on the lives of people with genetic syndromes. Greater awareness and recognition of movement problems in CdLS and FXS is required, and although specialist services may already be aware of some of the above issues, there should be an increased emphasis on ensuring that community services are aware of the needs of individuals with genetic syndromes, including the implications of movement problems for support needs and quality of life.

En réponse à des signaux environnementaux, la cellule module son programme transcriptionnel afin de mener à une expression spatio-­temporelle adéquate des gènes. L’orchestration d’une telle adaptation repose entre autres sur la séquence primaire du génome, son organisation au sein de la chromatine, ainsi que sa structure tridimensionnelle au sein du noyau. De plus, de nombreux régulateurs permettent d’intégrer ces différents niveaux de régulation afin de contrôler l’activité de l’ARN polymérase II. Dans ce contexte, le complexe cohésine et son facteur de charge sur l’ADN, NIPBL, jouent un rôle clé dans l’interconnexion fonctionnelle entre l’organisation 3D du génome et la transcription. En effet, ces facteurs modulent l’activation de la transcription en rapprochant des régions enhancers de promoteurs et participent à la formation de domaines d’interactions chromosomiques. Par ailleurs, des mutations de NIPBL et du complexe cohésine sont associées au Syndrome de Cornelia de Lange (CdLS), une pathologie caractérisée par une altération de l’expression des gènes. Toutefois, les mécanismes moléculaires impliqués dans la régulation de la transcription par NIPBL et cohésine sont encore méconnus. L’objectif général de mon projet de doctorat est de définir le rôle de NIPBL et du complexe cohésine dans la régulation du lien entre la topologie du génome et le contrôle de l’expression des gènes. Dans un premier temps, nous montrons que les gènes dérégulés dans le CdLS sont préférentiellement organisés au sein de communautés de gènes, des structures formées par des interactions d’éléments régulateurs non codants ainsi que de gènes dans l’espace chromosomique tridimensionnel. Au sein de cette organisation, les gènes affectés par des mutations de NIPBL ou de la sous-­unité SMC1A du complexe cohésine sont retrouvés positionnés à portée de régions occupées par cohésine et NIPBL et interagissent par l’intermédiaire de contacts promoteur-­promoteur. Dans un second temps, nous présentons des données suggérant un rôle de cohésine dans la régulation de l’initiation de la transcription et un rôle de NIPBL dans le contrôle de la relâche de la pause. Enfin, nous apportons des évidences d’une fonction de NIPBL et cohésine dans la régulation du niveau basal et de l’activation des gènes dont l’expression est stimulée par des hormones. Dans leur ensemble, ces travaux contribuent à l’amélioration des connaissances sur la contribution de l’architecture des chromosomes aux mécanismes généraux de la régulation de la transcription. / In response to environmental signals, the cell modulates its transcriptional program in order to carry out appropriate spatiotemporal gene expression. The orchestration of this adaptation relies on the primary sequence of the genome, its organization into chromatin, and its tridimensional structure inside the nucleus. Moreover, multiple regulators integrate these different regulation levels in order to control the activity of RNA polymerase II. In this context, the cohesin complex and its DNA loader, NIPBL, play a pivotal role in the functional interconnection between the 3D organization of the genome and transcription. Indeed, these factors modulate the activation of transcription by bringing enhancers and promoters into close proximity and participate in the formation of chromosome interaction domains. Moreover, mutations in NIPBL and the cohesin complex are associated with the Cornelia de Lange Syndrome (CdLS), a pathology characterized by gene expression changes. However, the exact molecular mechanisms involved in the regulation of transcription by NIPBL and cohesin are still not understood. The general aim of my doctoral research is to define the role of the cohesin complex and NIPBL in the regulation of the connection between genome topology and gene expression control. First, we show that genes deregulated in CdLS are preferentially organized into connected gene communities, structures emerging from the interactions of noncoding regulatory elements and genes in the three-­dimensional chromosomal space. Within this organization, genes affected by mutations in NIPBL and the SMC1A subunit of the cohesin complex are positioned within reach of NIPBL-­ and cohesin-­occupied regions through promoter-­ promoter interactions. In addition, we present data suggesting a role of the cohesin complex in the initiation of transcription and a role of NIPBL in the control of pause release. Finally, we show evidence of a function of NIPBL and cohesin in the regulation of the basal level and the activation of genes stimulated by hormones. Ultimately, this work aims to gain insight into the contribution of the architecture of chromosomes to the general mechanisms of transcriptional regulation.