03 Sep 1998

A 15-year study involving more than 100 families and 1,000 individuals has provided the first strong evidence of genetic susceptiblity to schizophrenia, within a stretch of chormosome 13. According to the international team, led by Ann Pulver at Johns Hopkins Medical Institutes, theirs is the first linkage data to meet stringent statistical standards. The study, reported in this month's Nature Genetics, also suggests that different genes may be responsible for for an increased risk of the disease in different families. The Hopkins-led team found evidence for susceptibility on chromosomes 8 and 22, though neither had the statistical strength of the chromosome 13 locus. Much evidence suggests that schizophrenia results from a combination of genetic susceptibility and environment. In studies of identical twins, for example, if one twin develops the disease, the other twin has a 46 percent chance of also having the disorder. Some suspected environmental risk factors include exposure to viruses in utero, birth trauma, head injury and stress.—June Kinoshita