From the September 19th edition of Psychiatric News:
By Jun YanTo read the entire article, click here.
As the search for genetic causes of schizophrenia intensifies, scientists have yet to find the specific defective genes at fault. The explanation, perhaps, is that variants are individually rare but located all over the genome.
A type of rare and spontaneous mutation that affects specific chromosomes has been linked to a substantial portion of schizophrenia cases and provides clues for the disease pathogenesis, as shown in several recent studies.
Copy-number variations (CNVs) refer to a type of genetic mutation in which chunks of DNA are repeated for a different number of times in a chromosome in different persons. The repeated DNA segments can range in size from thousands to millions of base pairs, may contain a gene or part of a gene, or disrupt a gene located in a chromosome, thus resulting in variations in the number of copies and the function of certain genes.
In two studies published in the July 30 Nature online, two groups of researchers separately found associations between the risk of psychotic disorders and rare CNVs. Deletions of substantial chunks of DNA at certain locations on the chromosomes were more common in individuals with schizophrenia or other psychoses than in healthy controls, the studies showed.
A number of studies have been published within the past few years that began to unravel the complex genetic patterns of mental illness, including but not limited to schizophrenia. Scientists have accumulated much evidence to suggest an important role of genetic predisposition in schizophrenia; however, unlike sickle-cell anemia or Huntington's disease, schizophrenia has a far more complex hereditary pattern and seems to involve a huge number of vulnerable mutations.