Genetic copy number variants in sib pairs both affected with schizophrenia

BACKGROUND: Schizophrenia is a complex disorder with involvement of multiple genes. METHODS: In this study, genome-wide screening for DNA copy-number variations (CNVs) was conducted for ten pairs, a total of 20 cases, of affected siblings using oligonucleotide array-based CGH. RESULTS: We found negative symptoms were significantly more severe (p < 0.05) in the subgroup that harbored more genetic imbalance (n ≧ 13, n = number of CNV-disrupted genes) as compared with the subgroup with fewer CNVs (n ≦ 6), indicating that the degree of genetic imbalance may influence the severity of the negative symptoms of schizophrenia. Four central nervous system (CNS) related genes including CCAAT/enhancer binding protein, delta (CEBPD, 8q11.21), retinoid × receptor, alpha (RXRA, 9q34.2), LIM homeobox protein 5 (LHX5, 12q24.13) and serine/threonine kinase 11 (STK11, 19p13.3) are recurrently (incidence ≧ 16.7%) disrupted by CNVs. Two genes, PVR (poliovirus receptor) and BU678720, are concordantly deleted in one and two, respectively, pairs of co-affected siblings. However, we did not find a significant association of this BU678720 deletion and schizophrenia in a large case-control sample. CONCLUSIONS: We conclude that the high genetic loading of CNVs may be the underlying cause of negative symptoms of schizophrenia, and the CNS-related genes revealed by this study warrant further investigation.