A new study has mapped out the human genome pinpointing five major mental illness linked to common, inherited genetic traits, according to a news release.
"Researchers funded in part by the National Institutes of Health found that the overlap was highest between schizophrenia and bipolar disorder; moderate for bipolar disorder and depression and for ADHD and depression; and low between schizophrenia and autism," the NIH said in a news release. "Overall, common genetic variation accounted for 17-28 percent of risk for the illnesses."
The study results were published in the journal Nature Genetics.
"Since our study only looked at common gene variants, the total genetic overlap between the disorders is likely higher," explained Naomi Wray, Ph.D. External Web Site Policy, University of Queensland, Brisbane, Australia, who co-led the multi-site study by the Cross Disorders Group of the Psychiatric Genomics Consortium (PGC). "Shared variants with smaller effects, rare variants, mutations, duplications, deletions, and gene-environment interactions also contribute to these illnesses."
The new genetic evidence linking schizophrenia and depression may be a significant discovery that will help future diagnostics and research, according to researchers. Scientists believe the findings will lead to new research into ADHD, autism, and schizophrenia-autism connections.
"The overlap in heritability attributable to common genetic variation was about 15 percent between schizophrenia and bipolar disorder," NIH said. "About 10 percent between bipolar disorder and depression, about 9 percent between schizophrenia and depression, and about 3 percent between schizophrenia and autism."
"Such evidence quantifying shared genetic risk factors among traditional psychiatric diagnoses will help us move toward classification that will be more faithful to nature," said Bruce Cuthbert, Ph.D., director of the NIMH Division of Adult Translational Research and Treatment Development and coordinator of the Institute's Research Domain Criteria (RDoC) project, which is developing a mental disorders classification system for research based more on underlying causes.
