deCODE Discovers a Variation in the Sequence of the Genome Conferring Risk of Atrial Fibrillation
Sunday July 1, 1:08 pm ET
Launches deCODE AF(TM), A Test for the Risk Variant Aimed at the Prevention of Stroke
REYKJAVIK, Iceland, July 1 /PRNewswire-FirstCall/ -- A paper published today in the journal Nature describes the discovery by scientists at deCODE genetics (Nasdaq: DCGN - News), in collaboration with academic colleagues in Iceland, the United States, Sweden and China, of two common single-letter variations in the genome (SNPs) conferring risk of atrial fibrillation (AF). AF is the most common cardiac arrhythmia and is also the leading cause of cardiogenic stroke. The variants, located on chromosome 4q25, confer an approximately 70% and 40% increase above average risk of AF, respectively, per copy carried. Approximately one third of people of European ancestry carry at least one copy of one of the risk variants, and deCODE's results show that those who carry two copies of the more powerful variant are at a more than 250% greater likelihood of AF than those who carry neither variant. The gene nearest to these SNPs, PITX2, is known to play an important role in the development of the heart.
deCODE also today launched deCODE AF(TM), a reference laboratory test for the variants. Because AF is the biggest risk factor for cardiogenic stroke, the company believes that testing for these variants will provide doctors with a targeted and cost-effective means of identifying those who should be intensively monitored for AF. Current best clinical practice recommends that stroke patients with AF can significantly reduce their risk of a second stroke by taking the anticoagulant drug warfarin.
"This is an important discovery with an immediate clinical application. Transient AF is difficult to detect in many patients, and it is impractical and too costly to conduct extended cardiac monitoring on all patients with stroke and transient ischemic attack. With the discovery of these variants, and the availability of a test to detect them, doctors may now be able focus monitoring on those most likely to have transient AF and then match therapy to the etiology of an individual's disease. This study is also impressive in that it took us only seven months from the beginning of the search for AF variants to today's publication and the launch of the test. This speaks very clearly to the power of our gene discovery capabilities and our product development group," said Kari Stefansson, CEO of deCODE and a board-certified neurologist.
deCODE discovered the variants, the "T" alleles of SNPs rs2200733 and rs10033464, through analysis of more than more than 300,000 SNPs in a total of more than 5,000 Icelanders with atrial fibrillation and/or atrial flutter as well as healthy control subjects. These findings were subsequently replicated in case-control cohorts from Iceland, the Massachusetts General Hospital in Boston, and the Karolinska Institute in Stockholm, including a total of 18,000 subjects. The stronger variant was also confirmed in a Han Chinese population from Hong Kong. In this group the variant conferred a slightly smaller increase in risk than in the other cohorts, but 75% of those studied carried at least one copy. Thus while the population-attributable risk (PAR) - roughly the proportion of cases that not exist were these variants not present - of the two variants in people European ancestry is approximately 20%, the first variant alone has a PAR of nearly 35% in Han Chinese. The article is published today in the online edition of Nature at www.nature.com and will appear in an upcoming print edition of the journal.
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