Schizophrenia Daily News Blog

Largest Genetic Study Shed Light on Some Illnesses Affecting the Brain

The UK-based Wellcome Trust Case Control Consortium, has recently announced some preliminary results from the largest ever study of the complex genetics behind some common diseases. Unexpected underlying links between the diseases studied, as varied as heart disease, rheumatoid arthritis and bipolar disorder, were found.

Although schizophrenia was not directly studied, some overlapping discoveries were made, and the discoveries are hoped to further the advancement of schizophrenia knowledge.

According to the researchers in the journal Nature, referring to the genes associated with bipolar disorder: "Increasing evidence suggests an overlap in genetic susceptibility with schizophrenia, a psychotic disorder with many similarities with BD [bipolar disorder]." And, "Pathogenesis [the pathway to illness] is poorly understood but there is robust evidence for a substantial genetic contribution to risk."

Referring to all the diseases studied, Professor Peter Donnelly, Chair of the Consortium, who is based at the University of Oxford stated, "Many of the most common diseases are very complex, part 'nature' and 'nurture', with genes interacting with our environment and lifestyles. By identifying the genes underlying these conditions, our study should enable scientists to understand better how disease occurs, which people are most at risk and, in time, to produce more effective, more personalised treatments."

Genes studied that have been particularly associated with both schizophrenia and bipolar disorder were DAOA, DISC1, NRG1 and DTNBP1, as well as possibly GABRB1 (GABA), and GRM7 (glutamate) and SYN3 (synapsinIII). An associated gene of particular interest was KCNC2 which is associated with episodic central nervous system disease, including seizures, ataxias, and paralyses, and which the researchers surmise may also extend to episodic disturbances of mood and behavior.

Dr. Nick Craddock (psychiatric genetics researcher in Wales) who recently became a scientific advisor to a nonprofit patient-led organization in the UK called “MDF The BiPolar Organisation” helped recruit patients for the Wellcome Trust genetic study.

Dr. Craddock's hope is that within a generation or two many people who would now be diagnosed with bipolar disorder or schizophrenia will receive a completely different diagnosis because we will better understand the actual underlying physiology of their precise illness. And the people who do retain the diagnoses of bipolar disorder and schizophrenia will also have better treatment for the actual underlying causes of the illnesses rather than just treatment for the symptoms. These treatments may include a combination of lifestyle changes, counseling or treatments designed to combat adverse hormonal changes.

The study, which took over two years and analyzed DNA samples from 17,000 people across the UK, used the Affymetrix chip (see here and here for related info). It brought together 50 leading research groups and 200 scientists in the field of human genetics from dozens of UK (United Kigndom) institutions and has substantially increased the number of genes known to play a role in the development of these common illnesses.

As the study was done in Europe, the Wellcome Trust’s findings apply to populations of European descent and will need to be verified in other races.

With the new information about the DNA variations affecting the biological pathways underlying each of the diseases, the researchers hope that as the pathways are analyzed, new drugs and treatments will emerge.

The results from 7 of their disease studies are being published this week in the journals Nature and Nature Genetics.

Read the BBC News Story: Scientists make bipolar gene find

Read the New York Times Story: Researchers Detect Variations in DNA That Underlie Seven Common Diseases (free registration required)

Read the Welcome Trust Press Release: Largest ever study of genetics of common diseases: Wellcome Trust Case Control Consortium and genetics of seven common diseases

Original Source Abstract: Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls (Nature, Vol 447, 7 June 2007)

Read the MDF The BiPolar Organisation Article: New Partnership with Leading Bipolar Disorder Research Professor