WASHINGTON -- Using a unique database of genetic information from Iceland's small and inbred population, researchers said they had discovered genetic clues about schizophrenia, asthma and even stroke and anxiety.

They have started work to develop better drugs to treat asthma and schizophrenia, based on their findings, and say the research shows how important genes are in disease.

"I believe the majority of human destinies have a genetic component," Reuters quoted Dr. Kari Stefansson, chief executive officer of Iceland-based Decode Genetics as saying in a telephone interview.

Since the discovery of human genetics, the argument has been about how much of biology is due to nature -- the genes -- and how much to nurture -- the environment.

Stefansson said his research is revealing that people have built-in tendencies even for diseases thought to be brought on by lifestyle and environment -- such as anxiety and stroke. "Anxiety -- that was one I was a little bit skeptical of in the beginning," Stefansson said. "I always thought anxiety was inseparable from the human condition."

Decode trolls an unusual database of genetic information set up in Iceland after the population voted to allow the DNA to be pooled for scientific study.

The researchers looked at the DNA of 26 extended families, each with at least one member diagnosed with panic disorder, and found common genetic changes on chromosome 9.

These may eventually help explain tendencies toward a range of anxiety-related conditions such as panic disorder, phobias and general anxiety disorder, decode's researchers told a meeting of the American Society of Human Genetics in Baltimore.

Stroke Gene Stefansson's team, working with the National University Hospital in Reykjavik, also found a gene associated with stroke, which they have named STRK 1. It controls an enzyme found in the artery walls and may help predispose some people to the buildup of material in blood vessels that can break off and cause a stroke or heart attack. "It is not one of the diseases in which you would have thought that genetics played the most important role," Stefansson said. "But if you think about it, in genetics your genome is a blueprint. You inherit a predisposition."

Other researchers have long been looking for a gene associated with stroke. A team at the JFK Medical Center in Edison, New Jersey told the same meeting they had tracked down a link with mutations in a gene called NOS3, which controls an enzyme called nitric oxide synthase.

Many teams have thought this gene, which is different from STRK 1, might be a suspect and the study of 400 New Jersey residents suggests it may be, the researchers said.

Many teams have also found genes associated with schizophrenia but Stefansson said his team found a gene called neuregulin 1 that was associated with schizophrenia in every Icelandic patient. "In our population the neuregulin gene in the major gene," Stefansson said. "There are always going to be other genes that influence the disease."

He said other researchers in the United States and Germany had replicated the findings and the company was working to find a drug that may affect this particular genetic function, perhaps providing a better treatment for schizophrenia. Current drugs have unpleasant side-effects and patients do not like to take them.

Several teams of researchers, including the Decode Team, also told the meeting they had found genes associated with asthma and were looking at ways to find out which asthma patients will respond better to a variety of asthma drugs.