Several Common Genetic Variants Found to be Associated With Mental Illness
New findings represent a significant advance in understanding the causes of schizophrenia and bipolar disorder.
As one of the leaders of an international research consortium, Mount Sinai School of Medicine researchers have discovered that several common genetic variants contribute to a person’s risk of schizophrenia and bipolar disorder, or manic-depressive illness. Two just-released studies provide new evidence that 11 genomic regions have a strong correlation with mental illness, including six areas not previously discovered. The researchers also found that some of these DNA variations contribute to both diseases.
The findings provide fresh insight into the causes of these diseases and may lead to new, more effective treatment options. The data are published in the September 18 issue of Nature Genetics.
"Schizophrenia and bipolar disorder are debilitating illnesses affecting millions of people around the world, and existing therapies for these people are ineffective as long-term options," said Pamela Sklar, MD, PhD, Chief of the Division of Psychiatric Genomics in the Department of Psychiatry and Professor of Psychiatry at Mount Sinai School of Medicine and lead author on the bipolar study. "We have been hard at work trying to determine genetic risk for these diseases so that we can intervene earlier and develop new therapies with which to treat them. Through this research, we are an important step closer to making that possible."
In the first study, the investigators used the DNA of 7,481 individuals with bipolar disorder and 9,250 healthy individuals to look at millions of DNA sites that are known to have different genetic sequences. In the second study, another team evaluated the same DNA sites in more than 17,000 people with schizophrenia. In these two genome-wide association studies, the scientists found several of these DNA sites – also known as DNA variants, or SNPs – in different genes and pathways showed strong association evidence with the diseases, some with bipolar disorder, some with schizophrenia, and some with both.
"Until recently, psychiatric research has understood the genetic basis of mental illness only very poorly," said Shaun Purcell, PhD, Associate Professor of Psychiatry at Mount Sinai School of Medicine and co-author with Dr. Sklar on the schizophrenia study. "Our research has helped us begin to elucidate the genetic structure of bipolar disorder and schizophrenia, and will, we hope, provide a new foundation to build upon in improving treatments and the quality of life of these patients."
Schizophrenia and bipolar disorder are common and often devastating brain disorders. Some of the most prominent symptoms in schizophrenia are persistent delusions, hallucinations, and cognitive problems. Bipolar disorder is characterized by episodes of severe mood problems including mania and depression. Both affect about one percent of the world’s population and usually strike in late adolescence or early adulthood.
Despite the availability of treatments, these illnesses are usually chronic, and response to treatment is often incomplete, leading to prolonged disability and personal suffering. Family history, which reflects genetic inheritance, is a strong risk factor for both schizophrenia and bipolar disorder, and it has generally been assumed that dozens of genes, along with environmental factors, contribute to disease risk.
"This research represents a significant step forward in understanding the genetic risk factors behind mental illness, paving the way for a new era in psychiatry," said Dennis S. Charney, MD, Anne and Joel Ehrenkranz Dean of Mount Sinai School of Medicine and the Executive Vice President for Academic Affairs of The Mount Sinai Medical Center. "Mount Sinai has a long history of psychiatric research dating back more than 100 years, and psychiatric genomics is emerging as an increasingly critical area for earlier intervention and better treatments for these diseases. We are pleased to be leading the charge in this area."
The studies were conducted by the Psychiatric Genome-Wide Association Study Consortium, the world’s largest consortium in psychiatry, which was formed in 2007. More than 250 researchers from more than 20 countries work in an unparalleled spirit of cooperation to advance knowledge of the genetic causes of mental illness. Crucial to the success of the project is the willingness of many groups to share genetic data from tens of thousands of patients collected over many years.
The research was funded by numerous European, U.S., and Australian funding bodies. Funds for coordination of the consortium were provided by the U.S. National Institute of Mental Health.
About The Mount Sinai Medical Center
The Mount Sinai Medical Center encompasses both The Mount Sinai Hospital and Mount Sinai School of Medicine. Established in 1968, Mount Sinai School of Medicine is one of the leading medical schools in the United States. The Medical School is noted for innovation in education, biomedical research, clinical care delivery, and local and global community service. It has more than 3,400 faculty in 32 departments and 14 research institutes, and ranks among the top 20 medical schools both in National Institutes of Health (NIH) funding and by U.S. News & World Report.
The Mount Sinai Hospital, founded in 1852, is a 1,171-bed tertiary- and quaternary-care teaching facility and one of the nation’s oldest, largest and most-respected voluntary hospitals. In 2011, U.S. News & World Report ranked The Mount Sinai Hospital 16th on its elite Honor Roll of the nation’s top hospitals based on reputation, safety, and other patient-care factors. Of the top 20 hospitals in the United States, Mount Sinai is one of 12 integrated academic medical centers whose medical school ranks among the top 20 in NIH funding and U.S. News & World Report and whose hospital is on the U.S. News & World Report Honor Roll. Nearly 60,000 people were treated at Mount Sinai as inpatients last year, and approximately 560,000 outpatient visits took place.
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