Japan scientists link strokes to gene variant

HONG KONG, Jan 8 (Reuters) Japanese researchers have identified a gene variant which appears to predispose a person to strokes, but it seems more prevalent in Asians than in those of European or African descent.

In a paper to be published in February in Nature Genetics, researchers said the presence of the variant raised the risk of cerebral infarction, the most common type of stroke, by 40 per cent.

Cerebral infarction happens when blood supply to a part of the brain is obstructed, resulting in death or serious damage to brain cells. The obstruction can be caused by a blood clot, a build-up of fatty deposits in blood vessels or cancerous cells.

The researchers studied 1,112 Japanese individuals and found that the variant of the gene PRKCH turned up more frequently in those who had had a stroke. The variant also appeared to be linked to an enzyme, rendering it more active.

''The risk variant makes the enzyme more active, and that is abundantly expressed in a variety of different cell types in blocked arteries, which can ultimately lead to a stroke,'' they wrote.

''Arteries with more severe blockages tended to have higher levels of PKC-eta (the enzyme).'' Lead researcher Michiaki Kubo, a laboratory head at Japan's Institute of Physical and Chemical Research, said the genetic variant was independent of other conventional risk factors such as age, sex, hypertension, smoking and drinking.

''Although many genetic and environmental factors contribute to the pathogenesis of atherosclerosis, we think that this will be one of the important factors for atherosclerosis,'' Kudo wrote in an email reply to Reuters.

Atherosclerosis is a hardening of the arteries, caused by fatty deposits in the bloodstream.

The identification of this variant could open the way to further studies on stroke prevention.

Kubo recommended that carriers be monitored intensively.

While a standard blood pressure of 140/90 mmHg (millimetres of mercury) would be acceptable for non-carriers, carriers should keep their blood pressure at a lower level.

However, the researchers added that this PRKCH variant is extremely rare in individuals of European or African descent, and therefore may not have a significant effect on the genetic susceptibility to stroke in non-Asian populations.

Stroke is the third most common cause of death in developed countries, exceeded only by coronary heart disease and cancer, according to the World Health Organisation.

Worldwide, 3 million women and 2.5 million men die from strokes each year. In the United States, someone dies of stroke every three minutes.

REUTERS PDM VC0925