AMPA receptor GluA2 subunit defects are a cause of neurodevelopmental disorders

Abstract

Neurodevelopmental disorders; AMPA; GluA2

Trastorns del neurodesenvolupament; AMPA; GluA2

Trastornos del neurodesarrollo; AMPA; GluA2

AMPA receptors (AMPARs) are tetrameric ligand-gated channels made up of combinations of GluA1-4 subunits encoded by GRIA1-4 genes. GluA2 has an especially important role because, following post-transcriptional editing at the Q607 site, it renders heteromultimeric AMPARs Ca2+-impermeable, with a linear relationship between current and trans-membrane voltage. Here, we report heterozygous de novo GRIA2 mutations in 28 unrelated patients with intellectual disability (ID) and neurodevelopmental abnormalities including autism spectrum disorder (ASD), Rett syndrome-like features, and seizures or developmental epileptic encephalopathy (DEE). In functional expression studies, mutations lead to a decrease in agonist-evoked current mediated by mutant subunits compared to wild-type channels. When GluA2 subunits are co-expressed with GluA1, most GRIA2 mutations cause a decreased current amplitude and some also affect voltage rectification. Our results show that de-novo variants in GRIA2 can cause neurodevelopmental disorders, complementing evidence that other genetic causes of ID, ASD and DEE also disrupt glutamatergic synaptic transmission.

Supported by the Wellcome Trust (WT093205MA and WT104033AIA), Medical Research Council (H.H. and D.M.K.), European Community’s Seventh Framework Programme (FP7/2007‐2013, under grant agreement No. 2012‐305121 to H.H.), Muscular Dystrophy Association (MDA), Muscular Dystrophy UK, The MSA Trust, Ataxia UK, The Sparkes Children’s Medical Research Charity, The Great Ormond Street Hospital Charity, Rosetrees Trust, Brain Research UK, The UK HSP Society, The European Union’s Horizon 2020 research and innovation programme Solve-RD project (No 779257), The Pakistan Council (Scholarship to HT), The National Natural Science Foundation of China (31671114, 81871079, 81330027, and 81525007 to H.G. and K.X.), the US National Institutes of Health (NIH grant R01MH101221 to E.E.E), the National Institute for Health Research (NIHR) University College London Hospitals (UCLH) and the Biomedical Research Centre (BRC)