 Multiple rare structural variants of relatively recent evolutionary origin are recognized as important risk factors for schizophrenia SZ and other neurodevelopmental disorders e.g., autism spectrum disorders, mental retardation, epilepsy with odds ratios as high as 7-30 Sebat et al. 2009; Malhotra et al. 2011; Heinzen et al. 2010; Weiss et al. 2008; McCarthy et al. 2009. We have found a de novo structural rearrangement on chromosome 9p24.1 in two psychotic patients. One of the genes in this region is the gene encoding glycine decarboxylase GLDC, which affects brain glycine metabolism. GLDC encodes the glycine decarboxylase or glycine cleavage system P-protein, which is involved in degradation of glycine in glia cells. Carriers of the GLDC triplication would be expected to have low levels of brain Gly, resulting in NMDA receptor-mediated hypofunction, which has been strongly implicated in the pathophysiology of schizophrenia Olney Farber, 1995; Coyle, 2006; Javitt, 2007. 