New gene test could help to prevent strokes

A new genetic test, developed by the Icelandic based company deCODE Genetics, in collaboration with academic colleagues from Iceland, Sweden, the United States and China, may help with the early identification of people with atrial fibrillation (AF), a common heart abnormality characterised by momentary heart palpitations, and believed to be the leading cause of stroke.

The results of a clinical trial of the test, published in the journal Nature Genetics last week, indicate that two 'spelling mistakes' in the genetic code, known as gene variants, significantly increased the risk AF. They found that at least one of the variants was present in one in three European descendants, and three in four Chinese descendants, studied.

'This is an important discovery with immediate clinical application', says Kari Stefansson, neuroscientist and Chief Executive of deCODE. 'With the discovery of these variants, and the availability of a test to detect them, doctors may now be able to focus monitoring on those most likely to have transient AF', he adds.

With a few exceptions, humans carry two copies of every gene, one from each parent. The researchers estimate that those who inherit a single copy of one of the gene variants from either parent have a 70 per cent or 40 per cent chance of being affected by AF, depending on which variant they carry. However those who inherit a copy from both parents may have double those risks.

The researchers carried out a genome-wide search on a group of 5,000 Icelanders with AF, to see which gene variants might be linked with the condition. After discovering the two variants in this population, they then looked for them in 18,000 people from other affected populations, in Sweden, the US and Hong Kong. This confirmed that the gene variants were a significant indicator of AF for people of both European and Han Chinese descent.

'Transient AF is difficult to detect in many patients', says Stefansson, claiming that it is 'impractical' and 'too costly' to closely monitor all patients affected by heart palpitations and stroke. The new test, he hopes, will target treatment and intensive monitoring to those who are at greatest risk.

However, in the long run the test must be evaluated in the clinic before it is known whether it actually leads to improved health, warns the UK's Public Health Genetics (PHG) Foundation, a charity aimed at promoting responsible and evidence-based biomedical science.