Gene research: A group of researchers from Trinity College, Dublin has identified three genes which make people susceptible to schizophrenia and are now encouraging Irish people with psychotic disorders to get involved in their project.
The genetic association study of psychotic disorders is one of the largest studies of its type in the State. It is trying to pinpoint the genes which contribute to schizophrenia and other psychotic illnesses. It is also trying to establish if the Irish population's genetic susceptibility to the disorder varies greatly from other populations.
The research group, based at St James's Hospital, is headed by Prof Michael Gill with Dr Aiden Corvin as principal investigator.
The findings could have huge implications for improving treatment options, according to research group member, psychiatrist Dr Jeanne-Marie Nangle.
"By understanding how these genes function and contribute to psychosis, we will gain better insight into the neurobiology of schizophrenia and other psychotic illnesses," she said.
The open-ended project, which has been going on for more than three years, has already involved 400 people but the researchers are seeking up to 1,000 people with schizophrenia, schizo-affective disorder or bi-polar affective disorder.
Schizophrenia affects about one in every hundred people and usually manifests itself in adolescence or early adulthood.
It is characterised by disturbances in a person's thoughts and behaviour. Symptoms can include delusions, hallucinations and a withdrawal from family and friends.
No single cause of schizophrenia has ever been identified but genetic factors are thought to contribute to about 80 per cent of schizophrenia risk.
Structural brain changes have been found in people at risk of psychotic disorders and further brain changes become evident as people go on to develop the disorder.
Other factors include environmental effects such as maternal infection in pregnancy and difficulties during delivery or in the first weeks of life.
Scientists have identified a number of broad chromosomal regions which are likely to harbour genes which make people susceptible to psychotic disorders.
While the TCD researchers had identified three genes, they still had to discover how these genes increased the risk, Dr Nangle said.
For example, one of the genetic variants was found in 19 per cent of people with schizophrenia but it was also found in 12 per cent of unaffected individuals. "This reflects the genetic complexities that underlie the disorders."
As the group is only researching the illness in the indigenous Irish population, it is seeking people whose parents and grandparents on both sides are Irish.
Evidence had shown that different genes may contribute to the disorder in different populations, Dr Nangle said.
The group is excluding people with learning disabilities and is only seeking people whose psychotic disorder was not induced by drugs or other medical conditions.
The use of drugs such as LSD, cocaine, speed and marijuana has been sometimes known to mimic the psychotic symptoms of schizophrenia.
The research group, which has received funding from Science Foundation Ireland, has recruited participants from hospitals and through Schizophrenia Ireland.
Participants have to undergo a clinical interview and a brief neurological assessment, and to provide a blood sample for genetic analysis.
More information is available by contacting Dr Nangle or her colleagues at 01-608 2462 or by e-mail at schwaigs@tcd.ie
The group's website address is www.tcd.ie/psychiatry/neuropsychiatry
Schizophrenia Ireland runs a helpline for people with schizophrenia or their families. The number is 1890 621 631.
