1. Breitenkamp AF, Matthes J, Nass RD, Sinzig J, Lehmkuhl G, Nurnberg P, Herzig S. {{Rare Mutations of CACNB2 Found in Autism Spectrum Disease-Affected Families Alter Calcium Channel Function}}. {PLoS One};2014;9(4):e95579.
Autism Spectrum Disorders (ASD) are complex neurodevelopmental diseases clinically defined by dysfunction of social interaction. Dysregulation of cellular calcium homeostasis might be involved in ASD pathogenesis, and genes coding for the L-type calcium channel subunits CaV1.2 (CACNA1C) and CaVbeta2 (CACNB2) were recently identified as risk loci for psychiatric diseases. Here, we present three rare missense mutations of CACNB2 (G167S, S197F, and F240L) found in ASD-affected families, two of them described here for the first time (G167S and F240L). All these mutations affect highly conserved regions while being absent in a sample of ethnically matched controls. We suggest the mutations to be of physiological relevance since they modulate whole-cell Ba2+ currents through calcium channels when expressed in a recombinant system (HEK-293 cells). Two mutations displayed significantly decelerated time-dependent inactivation as well as increased sensitivity of voltage-dependent inactivation. In contrast, the third mutation (F240L) showed significantly accelerated time-dependent inactivation. By altering the kinetic parameters, the mutations are reminiscent of the CACNA1C mutation causing Timothy Syndrome, a Mendelian disease presenting with ASD. In conclusion, the results of our first-time biophysical characterization of these three rare CACNB2 missense mutations identified in ASD patients support the hypothesis that calcium channel dysfunction may contribute to autism.
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2. Kang V, Wagner GC, Ming X. {{Gastrointestinal Dysfunction in Children With Autism Spectrum Disorders}}. {Autism Res};2014 (Apr 21)
Gastrointestinal (GI) dysfunctions are frequently reported by parents of children with autism spectrum disorders (ASD) and have been recently recognized as a comorbid condition. However, the clinical significance of these GI dysfunctions remains to be delineated. This study describes the clinical characteristics, associated comorbid disorders, and endoscopic and colonoscopic evaluation of GI dysfunction in a cohort of 164 children with ASD evaluated at a pediatric neurology practice. Symptoms of GI dysfunction were prevalent: 49% of the children reported one or more chronic GI complaints, 22% exhibited diarrhea, 26% suffered from constipation. Furthermore 13% of the parents reported their children to suffer from bloating and/or being gassy and while 10% of the parents reported vomiting or gastroesophageal reflux problems. Similar rates of GI symptoms were reported among pre-school and school-aged children. Inflammation of the gut was found in 6 of the 12 subjects who underwent endoscopic and colonoscopic evaluations, however clinical symptoms did not predict the results of the evaluation. GI dysfunction was significantly associated with sleep disorders and food intolerance, but not with irritability or aggressiveness. In summary, GI dysfunction was prevalent in this cohort of children with ASD, observations consistent with the reports of parents and other clinicians. We conclude that the GI dysfunction in ASD requires proper evaluation and treatment. Autism Res 2014, : -. (c) 2014 International Society for Autism Research, Wiley Periodicals, Inc.
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3. Napoli E, Wong S, Hertz-Picciotto I, Giulivi C. {{Deficits in Bioenergetics and Impaired Immune Response in Granulocytes From Children With Autism}}. {Pediatrics};2014 (Apr 21)
Despite the emerging role of mitochondria in immunity, a link between bioenergetics and the immune response in autism has not been explored. Mitochondrial outcomes and phorbol 12-myristate 13-acetate (PMA)-induced oxidative burst were evaluated in granulocytes from age-, race-, and gender-matched children with autism with severity scores of >/=7 (n = 10) and in typically developing (TD) children (n = 10). The oxidative phosphorylation capacity of granulocytes was 3-fold lower in children with autism than in TD children, with multiple deficits encompassing >/=1 Complexes. Higher oxidative stress in cells of children with autism was evidenced by higher rates of mitochondrial reactive oxygen species production (1.6-fold), higher mitochondrial DNA copy number per cell (1.5-fold), and increased deletions. Mitochondrial dysfunction in children with autism was accompanied by a lower (26% of TD children) oxidative burst by PMA-stimulated reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase and by a lower gene expression (45% of TD children’s mean values) of the nuclear factor erythroid 2-related factor 2 transcription factor involved in the antioxidant response. Given that the majority of granulocytes of children with autism exhibited defects in oxidative phosphorylation, immune response, and antioxidant defense, our results support the concept that immunity and response to oxidative stress may be regulated by basic mitochondrial functions as part of an integrated metabolic network.
