New Genetic Clues to Schizophrenia Discovered

Author: Neomi Heroux

Ancient documents identify diseases with the symptoms of schizophrenia as far back as Egypt in the second millennium before Christ, and the condition has probably followed mankind through history. The word schizophrenia is less than 100 years old and the modern identification of the disease was first done by Dr. Emile Kraepelin in 1887 as a discrete mental illness. The exact cause of schizophrenia, as with other mental disorders has eluded research for years, but researchers believe that they are moving closer to the causes and the possibility of an effective treatment for the condition.

Schizophrenia is a not a single problem but a group of serious brain disorders. It can range from mild to severe and some people with the disease may be able to function well in daily life, while others need specialized, intensive care. Schizophrenia is not the same as a split personality or multiple personalities. The word does mean "split-mind," but it refers to a disruption of the usual balance of emotions and thinking. The disease usually appears in late adolescence or early adulthood, is more common in men than women, and even with effective treatment remains a chronic condition. Approximately 1% of the population suffers from schizophrenia.

Those with schizophrenia interpret reality abnormally and usually suffer from hallucinations, delusions and disordered thinking and behavior. They will usually withdraw into their own realm marked by psychosis. Schizophrenia can appear suddenly or develop gradually over months and may be unnoticeable at first.

In independent international studies, the same rare genetic variations in patients with schizophrenia were identified. The research indicates that three rare deletions in the human genome appear to increase the risk of developing the brain condition. Dr. Pamela Sklar, corresponding author of a paper appearing in Nature and director of genetics at Harvard Medical School, Boston said "These findings give a great deal of hope, for individuals with schizophrenia and their families, loved ones, and caregivers, that we're moving towards an under standing of the cause of the disease."

Researchers stressed that the research explained only a tiny fraction of why people might develop schizophrenia and additional work needs to look at the full spectrum of other types of genetic factors that might influence schizophrenia. Schizophrenia, like autism, tends to run in families, which is the reason to focus on genetic determinants of the disease. The paper in Nature compared the genomes of 3,300 individuals with schizophrenia against those of 3,200 individuals without the illness. "We looked at a relatively rare type of DNA change where people have a substantial portion of a chromosome either missing or extra. These are called copy number changes," Sklar explained. The consortium found three deletions on specific chromosomes that appeared multiple times in people with schizophrenia. Two of the deletions had never been recognized before. According to Sklar that triples the number of specific DNA areas that may be responsible for the disease.

Michael O'Donovan, lead author of the Nature Genetics study and professor of psychiatric genetics at Cardiff University in the United Kingdom, acknowledged "We've been working on schizophrenia for rather more years than we care to think, and successes have not been dramatic." Other researchers have looked at what are called "whole chapters" in the genome, his team honed in on what he described as tiny spelling differences. "In addition to rare variants, we were able to convincingly show that common variants are involved in schizophrenia, but we don't know how much of a role they play compared with rare variants." According to Donovan it means that all humans have genes for schizophrenia, but those who do not have it don't have enough of the genes or possibly have not been exposed to environmental stimulus.

The studies indicate a shift in focus for finding variants that affect the risk of schizophrenia. The search for rare variants may help identify groups of patients with different genetic causes for their diseases. This could lead to treatments tailored to different biological causes which would improve treatment outcomes.