Original Article - click here for text.
Molecular Psychiatry advance online publication 24 November 2009; doi: 10.1038/mp.2009.118
R J Delahanty1,8, J Q Kang2,8, C W Brune3, E O Kistner4, E Courchesne5, N J Cox6, E H Cook Jr4, R L Macdonald2 and J S Sutcliffe1,7
- 1Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
- 2Department of Neurology, Vanderbilt University, Nashville, TN, USA
- 3Department of Psychiatry, Institute for Juvenile Research, University of Illinois at Chicago, Chicago, IL, USA
- 4Department of Health Studies, The University of Chicago, Chicago, IL, USA
- 5Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
- 6Department of Medicine, The University of Chicago, Chicago, IL, USA
- 7Department of Psychiatry, Vanderbilt University, Nashville, TN, USA
Correspondence: Dr JS Sutcliffe, Center for Molecular Neuroscience, Departments of Molecular Physiology and Biophysics and Psychiatry, Vanderbilt University, Nashville, TN 37232-8548, USA. E-mail:jim.sutcliffe@vanderbilt.edu
8These two authors contributed equally to this work.
Received 7 July 2009; Revised 10 September 2009; Accepted 22 September 2009; Published online 24 November 2009.
Maternal 15q11-q13 duplication is the most common copy number variant in autism, accounting for 1–3% of cases. The 15q11-q13 region is subject to epigenetic regulation, and genomic copy number losses and gains cause genomic disorders in a parent-of-origin-specific manner. One 15q11-q13 locus encodes the GABAA receptor 3 subunit gene (GABRB3), which has been implicated by several studies in both autism and absence epilepsy, and the co-morbidity of epilepsy in autism is well established. We report that maternal transmission of a GABRB3 signal peptide variant (P11S), previously implicated in childhood absence epilepsy, is associated with autism. An analysis of wild-type and mutant 3 subunit-containing 132 or 332 GABAA receptors shows reduced whole-cell current and decreased 3 subunit protein on the cell surface due to impaired intracellular 3 subunit processing. We thus provide the first evidence of an association between a specific GABAA receptor defect and autism, direct evidence that this defect causes synaptic dysfunction that is autism relevant and the first maternal risk effect in the 15q11-q13 autism duplication region that is linked to a coding variant.