Delineating the Shared Genetics Across the Mood Disorders Spectrum

An important question in psychiatry is the extent of overlap between various psychiatric conditions. It has been more than a century since Emil Kraepelin first suggested a broad division between schizophrenia and bipolar disorder (BD) [see (1)], an idea that has largely endured until today. However, the distinction between major depressive disorder (MDD) and BD and their subtypes (together, known as mood disorders) is less clear, with differences between the ICD-11 and the DSM-5 in how these conditions are grouped.