A defective variant of the DISC1 gene first discovered from a Scottish pedigree, and carried a balanced translocation (1;11; q42.1; q14.3) that was strongly associated with major mental illness such as schizophrenia, depression, and bipolar disorder (St Clair et al., 1990; Millar et al., 2000). The gene discussed is DISC1; the disease is schizophrenia.