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Sci Rep 2016 Sep 28;6:34325. doi: 10.1038/srep34325.
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Gain-of-function defects of astrocytic Kir4.1 channels in children with autism spectrum disorders and epilepsy.

Sicca F , Ambrosini E , Marchese M , Sforna L , Servettini I , Valvo G , Brignone MS , Lanciotti A , Moro F , Grottesi A , Catacuzzeno L , Baldini S , Hasan S , D'Adamo MC , Franciolini F , Molinari P , Santorelli FM , Pessia M .

Dysfunction of the inwardly-rectifying potassium channels Kir4.1 (KCNJ10) represents a pathogenic mechanism contributing to Autism-Epilepsy comorbidity. To define the role of Kir4.1 variants in the disorder, we sequenced KCNJ10 in a sample of affected individuals, and performed genotype-phenotype correlations. The effects of mutations on channel activity, protein trafficking, and astrocyte function were investigated in Xenopus laevis oocytes, and in human astrocytoma cell lines. An in vivo model of the disorder was also explored through generation of kcnj10a morphant zebrafish overexpressing the mutated human KCNJ10. We detected germline heterozygous KCNJ10 variants in 19/175 affected children. Epileptic spasms with dysregulated sensory processing represented the main disease phenotype. When investigated on astrocyte-like cells, the p.R18Q mutation exerted a gain-of-function effect by enhancing Kir4.1 membrane expression and current density. Similarly, the p.R348H variant led to gain of channel function through hindrance of pH-dependent current inhibition. The frequent polymorphism p.R271C seemed, instead, to have no obvious functional effects. Our results confirm that variants in KCNJ10 deserve attention in autism-epilepsy, and provide insight into the molecular mechanisms of autism and seizures. Similar to neurons, astrocyte dysfunction may result in abnormal synaptic transmission and electrical discharge, and should be regarded as a possible pharmacological target in autism-epilepsy.

PubMed ID: 27677466
PMC ID: PMC5039625
Article link: Sci Rep
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: aqp4 dag1 kcnj10 kcnj16 trpv4

Disease Ontology terms: autism spectrum disorder [+]

Article Images: [+] show captions
References [+] :
Ambrosini, Genetically induced dysfunctions of Kir2.1 channels: implications for short QT3 syndrome and autism-epilepsy phenotype. 2014, Pubmed, Xenbase