1. Leonard H, Cobb S, Downs J. {{Clinical and biological progress over 50 years in Rett syndrome}}. {Nat Rev Neurol};2016 (Dec 09)
In the 50 years since Andreas Rett first described the syndrome that came to bear his name, and is now known to be caused by a mutation in the methyl-CpG-binding protein 2 (MECP2) gene, a compelling blend of astute clinical observations and clinical and laboratory research has substantially enhanced our understanding of this rare disorder. Here, we document the contributions of the early pioneers in Rett syndrome (RTT) research, and describe the evolution of knowledge in terms of diagnostic criteria, clinical variation, and the interplay with other Rett-related disorders. We provide a synthesis of what is known about the neurobiology of MeCP2, considering the lessons learned from both cell and animal models, and how they might inform future clinical trials. With a focus on the core criteria, we examine the relationships between genotype and clinical severity. We review current knowledge about the many comorbidities that occur in RTT, and how genotype may modify their presentation. We also acknowledge the important drivers that are accelerating this research programme, including the roles of research infrastructure, international collaboration and advocacy groups. Finally, we highlight the major milestones since 1966, and what they mean for the day-to-day lives of individuals with RTT and their families.
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2. Peper CL, van der Wal SJ, Begeer S. {{Autism in Action: Reduced Bodily Connectedness during Social Interactions?}}. {Front Psychol};2016;7:1862.
Autism is a lifelong disorder, defined by deficits in social interactions and flexibility. To date, diagnostic markers for autism primarily include limitations in social behavior and cognition. However, such tests have often shown to be inadequate for individuals with autism who are either more cognitively able or intellectually disabled. The assessment of the social limitations of autism would benefit from new tests that capture the dynamics of social initiative and reciprocity in interaction processes, and that are not dependent on intellectual or verbal skills. New entry points for the development of such assessments may be found in ‘bodily connectedness’, the attunement of bodily movement between two individuals. In typical development, bodily connectedness is related to psychological connectedness, including social skills and relation quality. Limitations in bodily connectedness could be a central mechanism underlying the social impairment in autism. While bodily connectedness can be minutely assessed with advanced techniques, our understanding of these skills in autism is limited. This Perspective provides examples of how the potential relation between bodily connectedness and specific characteristics of autism can be examined using methods from the coordination dynamics approach. Uncovering this relation is particularly important for developing sensitive tools to assess the tendency to initiate social interactions and the dynamics of mutual adjustments during social interactions, as current assessments are not suited to grasp ongoing dynamics and reciprocity in behavior. The outcomes of such research may yield valuable openings for the development of diagnostic markers for autism that can be applied across the lifespan.
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3. Shen IH, Lin SC, Wu YY, Chen CL. {{An Event-Related Potential Study on the Perception and the Recognition of Face, Facial Features, and Objects in Children With Autism Spectrum Disorders}}. {Percept Mot Skills};2016 (Dec 07)
The study investigated whether children with autism spectrum disorders (ASD) showed atypical patterns of brain specialization for face processing, whether the response to familiar and unfamiliar faces, facial features, and objects were different from typically developing children. Event-related potentials were recorded in 5- to 8-year-old children (12 children with ASD, 12 typically developing children) using passive viewing paradigm. The fastest P1 latencies to faces and the largest P1 amplitudes to objects were observed in both participant groups. Both groups exhibited larger N170 response to faces and eyes, F(3, 66) = 46.94, p < .0001). However, earlier P1 and N170 latencies were found on left hemisphere in children with ASD, respectively, F(1, 83) = 4.32, p = .04; F(1, 83) = 6.73, p = .01, indicating an atypical face processing pattern. All children showed a significant effect of familiarity for objects and mouths, F(1, 71) = 33.97, p < .0001; F(1, 71 = 15.94, p = .0002. Children with ASD revealed smaller negative central to faces relative to typically developing children. Face processing abnormalities revealed in children with ASD very likely exist. Lien vers le texte intégral (Open Access ou abonnement)
4. Urraca N, Potter B, Hundley R, Pivnick EK, McVicar K, Thibert RL, Ledbetter C, Chamberlain R, Miravalle L, Sirois CL, Chamberlain S, Reiter LT. {{A Rare Inherited 15q11.2-q13.1 Interstitial Duplication with Maternal Somatic Mosaicism, Renal Carcinoma, and Autism}}. {Front Genet};2016;7:205.
Chromosome 15q11-q13.1 duplication is a common copy number variant associated with autism spectrum disorder (ASD). Most cases are de novo, maternal in origin and fully penetrant for ASD. Here, we describe a unique family with an interstitial 15q11.2-q13.1 maternal duplication and the presence of somatic mosaicism in the mother. She is typically functioning, but formal autism testing showed mild ASD. She had several congenital anomalies, and she is the first 15q Duplication case reported in the literature to develop unilateral renal carcinoma. Her two affected children share some of these clinical characteristics, and have severe ASD. Several tissues in the mother, including blood, skin, a kidney tumor, and normal kidney margin tissues were studied for the presence of the 15q11-q13.1 duplication. We show the mother has somatic mosaicism for the duplication in several tissues to varying degrees. A growth competition assay in two types of stem cells from duplication 15q individuals was also performed. Our results suggest that the presence of this interstitial duplication 15q chromosome may confer a previously unknown growth advantage in this particular individual, but not in the general interstitial duplication 15q population.
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5. Wang Z, Hallac RR, Conroy KC, White SP, Kane AA, Collinsworth AL, Sweeney JA, Mosconi MW. {{Postural orientation and equilibrium processes associated with increased postural sway in autism spectrum disorder (ASD)}}. {J Neurodev Disord};2016;8:43.
BACKGROUND: Increased postural sway has been repeatedly documented in children with autism spectrum disorder (ASD). Characterizing the control processes underlying this deficit, including postural orientation and equilibrium, may provide key insights into neurophysiological mechanisms associated with ASD. Postural orientation refers to children’s ability to actively align their trunk and head with respect to their base of support, while postural equilibrium is an active process whereby children coordinate ankle dorsi-/plantar-flexion and hip abduction/adduction movements to stabilize their upper body. Dynamic engagement of each of these control processes is important for maintaining postural stability, though neither postural orientation nor equilibrium has been studied in ASD. METHODS: Twenty-two children with ASD and 21 age and performance IQ-matched typically developing (TD) controls completed three standing tests. During static stance, participants were instructed to stand as still as possible. During dynamic stances, participants swayed at a comfortable speed and magnitude in either anterior-posterior (AP) or mediolateral (ML) directions. The center of pressure (COP) standard deviation and trajectory length were examined to determine if children with ASD showed increased postural sway. Postural orientation was assessed using a novel virtual time-to-contact (VTC) approach that characterized spatiotemporal dimensions of children’s postural sway (i.e., body alignment) relative to their postural limitation boundary, defined as the maximum extent to which each child could sway in each direction. Postural equilibrium was quantified by evaluating the amount of shared or mutual information of COP time series measured along the AP and ML directions. RESULTS: Consistent with prior studies, children with ASD showed increased postural sway during both static and dynamic stances relative to TD children. In regard to postural orientation processes, children with ASD demonstrated reduced spatial perception of their postural limitation boundary towards target directions and reduced time to correct this error during dynamic postural sways but not during static stance. Regarding postural equilibrium, they showed a compromised ability to decouple ankle dorsi-/plantar-flexion and hip abduction/adduction processes during dynamic stances. CONCLUSIONS: These results suggest that deficits in both postural orientation and equilibrium processes contribute to reduced postural stability in ASD. Specifically, increased postural sway in ASD appears to reflect patients’ impaired perception of their body movement relative to their own postural limitation boundary as well as a reduced ability to decouple distinct ankle and hip movements to align their body during standing. Our findings that deficits in postural orientation and equilibrium are more pronounced during dynamic compared to static stances suggests that the increased demands of everyday activities in which children must dynamically shift their COP involve more severe postural control deficits in ASD relative to static stance conditions that often are studied. Systematic assessment of dynamic postural control processes in ASD may provide important insights into new treatment targets and neurodevelopmental mechanisms.
