WASHINGTON (AP) — The largest genetic study of mental illnesses to date finds five major disorders may not look much alike but they share some gene-based risks. The surprising discovery comes in the quest to unravel what causes psychiatric disorders and how to better diagnose and treat them.

The disorders — autism, attention deficit-hyperactivity disorder or ADHD, bipolar disorder, major depressive disorder and schizophrenia — are considered distinct problems. But findings published online Wednesday suggest they’re related in some way.