specific proteins have not been previously implicated in pathophysiology of mood or psychotic illness. The strong association we observe at chromosome 16p13.3 is of interest because it lies within the gene A2BP1, encoding ataxin 2-binding protein 1 isoform 4, a protein that binds to ataxin-2 and may contribute to the restricted pathology of familial neurodegenerative disease, spinocerebellar ataxia type 2. Disruption of A2BP1 has been described in association with neuropsychiatric phenotypes including autism,37 mental retardation and epilepsy.38 Other genes of potential interest that show association signals at the less stringent significance threshold of P<0.0001 (online Table DS3) include autism susceptibility candidate 2 (AUTS2) on chromosome 7q11.2; BSN, the gene encoding the protein bassoon which is thought to be involved in the organisation of the cytomatrix at the nerve terminals active zone which regulates neurotransmitter release and which is essential in regulated neurotransmitter release from a subset of brain glutamatergic synapses; PTPRG, encoding a member of the protein tyrosine phosphatase family which are signalling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle and oncogenic transformation; GRIK2 encoding glutamate receptor, ionotropic kainate 2 precursor (glutamate receptor 6) (GluR-6) (GluR6); and CDH12 encoding cadherin 12, type 2
