Schizophrenia Yields New Gene Clues
Bower, Bruce, Science News
Scientists' limited understanding of how genes contribute to schizophrenia just got a shot in the arm. Four independent research teams now report that one relatively small DNA segment, containing several hundred genes at most, includes a gene that confers a susceptibility to schizophrenia--at least in a substantial minority of cases.
The new studies support earlier evidence of a connection between schizophrenia and a gene somewhere in a short stretch of chromosome 6 (SN: 5/13/95, p.297). However, two other research efforts failed to link the chromosome 6 region to this severe mental disorder, which afflicts an estimated 1 in 100 people worldwide.
All six investigations appear in the November Nature Genetics.
Despite the contradictory results, evidence of a schizophrenia susceptibility site on chromosome 6 is "significant--and probably confirmed," write Eric Lander and Leonid Kruglyak, both geneticists at the Massachusetts Institute of Technology in an editorial accompanying the reports.
"I wouldn't go as far as that," responds Elliot S. Gershon, director of the neurogenetics branch of the National Institute of Mental Health in Bethesda, Md. "This new evidence is encouraging and a positive step forward, but further replications are still needed."
One study, which included data from the previous chromosome 6 analysis, consisted of 265 Irish families, each having at least two members diagnosed with schizophrenia or related psychotic disorders. A total of 1,408 individuals gave blood samples for DNA analysis.
Special enzymes snipped out DNA segments at 16 known locations. The researchers, led by Richard E. Straub of Virginia Commonwealth University in Richmond, analyzed the rates and patterns of alterations in the chemical sequence of these sections in both healthy and schizophrenic volunteers.
Only in the chromosome 6 area did variations show a statistical link to schizophrenia. In perhaps one-quarter of the families, a gene in this region raised the likelihood that a person would develop schizophrenia, Straub's team contends.
Both the identity of the gene and the way it works remain unknown.
An international study directed by Hans W. …