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Researchers from Decode Genetics, the Icelandic company that discovered genes for schizophrenia and osteoporosis, say they have found a variant gene that doubles the risk of heart attack and stroke. Results of the study are in Monday’s edition of Nature Genetics.

Twenty-nine percent of all heart attack patients in Iceland carry the gene, known as FLAP for 5-lipoxygenase activating protein, the study says, and it almost doubles their risk of the disease. The gene sends a chemical signal that activates white blood cells involved in inflammation.

The company used DNA analysis and statistical genetics to find these genes in Icelanders, and has shown that many of its findings apply to other populations, too. The company has started advanced clinical trials of a drug, licensed by the German company Bayer, that inhibits the enzyme made by the gene.

Dr. Richard P. Lifton of Yale, an expert on the genetics of cardiovascular disease, and Dr. David Altshuler, a medical geneticist at Harvard Medical School, expressed concern about the study. Lifton said as a reviewer he advised the journal to reject the article because the evidence linking the variant gene to heart attacks was “actually rather weak.”