GJA5 and schizophrenia: Of the genes located on chromosome 1q21.1 and disrupted by this CNV, the gap junction genes connexin 40 and connexin 50 participate directly in intercellular exchanges of neurotransmitters (e.g., glutamate) in the synaptic transmission of the central nervous system; and a matched case–control study of the two connexin genes found that mutations in connexin 50 were strongly correlated with schizophrenia (Ni et al., 2007; International Schizophrenia, 2008; Levinson et al., 2011).