Schizophrenia and bipolar disorder can be debilitating for the individual suffering, as well as family and friends. Medications can deliver some relief, but the most effective treatments will be developed as a result of intense research into the makeup of such psychological impairments.
Three genome-wide studies have identified an array of genetic variation that could be responsible for a minimum of one third of the genetic risk for schizophrenia. One study in particular traced both schizophrenia and bipolar disorder to the same area of chromosomes.
According to Thomas R. Insel, M.D., director of the National Institute of Mental Health (NIMH), part of the National Institutes of Health, this similar origination suggests some of the same genetic risks underlie schizophrenia and bipolar disorder, suggesting these disorders originate from some common vulnerability in brain development.
Each of the three studies, funded in part by the NIMH, implicated an area of Chromosome 6, which is known to harbor genes associated with immunity and the control of how and when genes turn on and off. Such a spot of association could offer help in explaining how environmental factors impact the risk for schizophrenia.
Pamela Sklar, M.D., Ph.D., of Harvard University and the Stanley Center for Psychiatric Research, who co-led the ISC team with Harvard’s Shaun Purcell, Ph.D. noted the common variants’ effects offer no statistical significance when studied alone. The same variants, when considered cumulatively, play a major role in which they account for at least one third of disease risk.
Sklar also highlighted that there was a substantial overlap in the genetic risk for schizophrenia and bipolar disorder that was specific to mental disorders. Researchers identified no association between the suspect gene variants and a variety of common non-psychiatric disorders. At the same time, the majority of genetic contributions to schizophrenia, estimated to be at least 70 percent heritable, remains unknown.
One of the strongest associations identified was seen in the vicinity of genes for the histones proteins. These proteins are designed to apply a molecular clamp on a gene’s process to turn on in response to the environment. Variation in the functioning of such regulatory mechanisms as a result of genetics could help to explain the environmental component that is consistently associated with schizophrenia risk.
Researchers anticipate these new findings could eventually help to identify multi-gene signatures or biomarkers for severe mental disorders. In relation to schizophrenia and bipolar disorder, both share genetic roots that appear to be specific to serious mental disorders and are not shared by non-psychiatric illnesses. Continued research into this area will help lead to the creation of effective treatments and perhaps even risk assessments and the identification of environmental triggers that intensify the disorders.