Study reveals that many psychiatric disorders arise from commonly shared genes

December 17, 2019
PORTLAND, Maine – Many distinct psychiatric diseases share a common genetic structure, according to new research by scientists at Maine Medical Center Research Institute (MMCRI) and the Psychiatric Genomics Consortium (PGC), an international team of investigators. Psychiatric disorders affect more than 25 percent of the population in a given year. In the largest-ever study of its kind, published in the journal Cell, researchers identified more than 100 genetic variants that affect the risk for more than one mental health condition.

A gene is made up of segments of DNA; an alteration in the DNA sequence produces a gene variant, which can increase or decrease the risk for disease. Many individual gene variants that affect the risk for specific psychiatric disorders have been identified. However, genes are often pleiotropic, meaning they produce multiple effects in the body, including showing up as multiple disorders.

“The big takeaway from this study for me is that although the classification system we use for treating psychiatric disorders assumes that each disorder is distinct from one another, these study results clearly contradict that view,” said study co-author Susan L. Santangelo, Sc.D., Director of the Center for Psychiatric Research at MMCRI and a member of the PGC. “Understanding that many of these disorders share biological risk factors from an early stage of development can give us more insight into how we might better diagnose and treat the disorders.”

To identify these multi-purpose gene variants, researchers used a technique called genome-wide association to analyze genetic data from 494,162 healthy control subjects and 232,964 people diagnosed with at least one of eight common psychiatric disorders. The analysis identified 109 gene variants that affect the risk for more than one psychiatric disorder. There was also a smaller set of 23 genes that were even more pleiotropic, affecting four or more disorders.

Certain disorders shared many variants, allowing the researchers to divide the conditions into three groups of genetically related conditions: disorders characterized by compulsive behaviors (anorexia nervosa, obsessive-compulsive disorder and, to a lesser extent, Tourette syndrome); mood and psychotic disorders (bipolar disorder, major depression and schizophrenia); and early-onset neurodevelopmental disorders (autism spectrum disorder, ADHD and Tourette syndrome).

The study identified several gene variants that had an especially broad effect on risk for a number of psychiatric disorders and may prove to be even more important in the prevention and treatment of these disorders. “Because these variants have such widespread influence, they may be better potential targets for developing new treatments, especially since these variants are characterized by their involvement in early neurodevelopment and also seem to play an important role in brain development,” Dr. Santangelo said.

About Maine Medical Center
Maine Medical Center (MMC), recognized as a Best Regional Hospital by U.S. News and World Report for 2018-2019, is a complete health care resource for the people of Greater Portland and the entire state, as well as northern New England. Incorporated in 1868, MMC is the state’s largest medical center, licensed for 637 beds and employing nearly 8,700 people. MMC's unique role as both a community hospital and a referral center requires an unparalleled depth and breadth of services, including an active educational program and a world-class biomedical research center. As a nonprofit institution, Maine Medical Center provides nearly 23 percent of all the charity care delivered in Maine. MMC is part of the MaineHealth system, a growing family of health care services in northern New England. For more information, visit