Excerpt from story by NICHOLAS WADE, New York Times

The long search for a gene that helps cause schizophrenia may at last be bearing fruit after many false starts and disappointments, scientists are reporting.

An errant gene first implicated among schizophrenic patients in Iceland has now turned up in a survey of Scottish patients, too, giving a clear confirmation of the earlier result.

The gene may be involved in remodeling the connections that brain cells make with one another, called synapses. Many of the Icelandic and Scottish patients have the same variant pattern in the gene, supporting the idea that when the gene does not work as designed, wrongly formed nerve-to-nerve wiring accumulates in the brain, giving rise to schizophrenia.

Not all schizophrenics carry the variant and many people carry it without a problem, an expected pattern in diseases caused by several genes. But in both populations, inheriting the variant form of the gene appears to double the risk of schizophrenia.

The finding, if correct, would bolster the strategy followed by Decode Genetics, a company based in Reykjavik that is using the Icelandic population to search for the genetic roots of common diseases like cancer, diabetes, heart disease and Parkinson's. The schizophrenia-related gene is one of the first it has found.

Dr. Kari Stefansson, a former Harvard neuropathologist who is the company's chief executive, said Decode and its partner, the drug company Roche, were developing new drugs to counteract the aberrant gene's effects but could not say when any would be ready for clinical testing.

A defect in neuregulin-1, he suggested, might lead to an accumulation of wrongly formed synapses, accounting for the progressive nature of the disease. It might also explain why environmental factors as well as heredity contribute to schizophrenia, as shown by the fact that if one identical twin has the disease the other has only a 30 to 50 percent chance of developing it.

Dr. Stefansson said he had a considerable emotional investment in the disease because his elder brother has schizophrenia.

The variation discovered by Decode Genetics is a set of seven genetic differences that spans the beginning of the neuregulin gene, which is located on the eighth of the 23 pairs of human chromosomes. Dr. Stefansson said he guessed that the seven changes might in some unexplained way be altering the amount of protein the gene could produce. ...

Dr. Kendler said the progress with the two genes "induces a bit more optimism in a field that has had some difficult times."