The availability of new technologies such as comparative genomic hybridization and SNP-arrays in GWA studies has enabled the identification of small chromosomal aberrations on a genome-wide scale. The first such studies of schizophrenia found increased overall rates of aberrations (Walsh et al., 2008; Xu et al., 2008). More recent studies have implicated specific chromosomal regions. These include microdeletions in chromosomal regions 1q21.1, 2p16.3, 15q11.2, and 15q13.3, as well as microduplication in chromosomal region 15q13.1 (International Schizophrenia Consortium, 2008; Kirov et al., 2009a; Need et al., 2009; Rujescu et al., 2009). All of these variants are found more frequently among patients than among controls, although the frequency of each individual variant in schizophrenia patients is low (<1%). Further studies are necessary to determine the penetrance, the mutation rate, and the full phenotypic spectrum associated with these aberrations. Some variants appear to be more frequent in patients with other central nervous system phenotypes such as mental disability, epilepsy, and autism (Mefford et al., 2008; Ben-Shachar et al., 2009; Helbig et al., 2009; Miller et al., 2009). This suggests that these disorders may have common etiological factors.
