Multiple independent linkage and association studies in diverse populations support a role for Disrupted-in-Schizophrenia 1 (DISC1) as a genetic risk factor in a range of major mental illnesses, including schizophrenia, depression and bipolar disorder.1 Arguably, the most persuasive evidence supporting a role for DISC1 in mental illness was gained from the initial studies of a large Scottish pedigree. This evidence concerns the gene DISC1 and bipolar disorder.