New Genetic Clues to Schizophrenia Discovered (Part 2)

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.