Two new studies have identified genetic activity that appears to be associated with schizophrenia, a serious brain disorder that alters a person's perceptions of reality, emotions and thought processes. Symptoms of the disorder, which affects about 1% of the world's population, typically surface during the late teens and 20s.In this study, Dr. Maria Karayiorgou of Rockefeller, University in New York and colleagues identified two genes/ located in a region of chromosome 22--a section of DNA that has previously been linked to schizophrenia--that appeared to play a role in the disease.
In their study, Karayiorgou's team analyzed DNA samples from more than 250 people with schizophrenia, their parents and a group of healthy individuals. The researchers included people with childhood onset schizophrenia, a rare form of the disease that strikes by age 12.The two genes are PRODH2, which encodes for a common brain enzyme, and DGCR6, a gene that is associated with nervous system development. Certain variations in the PRODH2 seemed to be more common in those with schizophrenia than in others, although the investigators could not rule out nearby DGCR6 as playing a role.
Karayiorgou felt that variation in the genes was over-represented in the patients with schizophrenia compared to the healthy people. More work is needed until we have a genetic profile of variation that could account for the schizophrenia in any given person. The researchers honed in on chromosome 22 because people who have deletions or damage in this portion of DNA are known to have a 30-fold greater risk of developing schizophrenia, she said.
In the second study, Sabine Bahn of the Babraham Institute in Cambridge, UK, and colleagues also identified genes on chromosome 22 that they believe may play a role in schizophrenia.
The team analyzed brain tissue from dead schizophrenia patients and compared them with similar samples from those with other psychiatric patients and healthy individuals. Patients with schizophrenia had nearly three times the gene expression of apolipoprotein L1, a protein that is manufactured by a family of genes called the apo L family. These genes play an important role in cholesterol transport. Cholesterol is important in the adult brain as well as during its early development.
The findings led the researchers to conclude that it is best to be confident in suggesting that abnormalities in the expression of these genes may be involved in the genesis of schizophrenia.
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