Eight new blood pressure genes discovered

Eight genetic variations that influence blood pressure are revealed in major new study<em> - News Release</em>

From a press release issued by the Global BPgen consortium

Monday 11 May 2009

Eight common genetic variations which have an influence on blood pressure have been identified in a new study by scientists at Imperial College London, working with 164 researchers from 93 centres in Europe and the USA.

High blood pressure affects 1 billion people worldwide and at least eighteen million people in the UK. It is a major risk factor for heart disease and stroke and causes at least seven million deaths worldwide each year. Although a number of lifestyle factors, such as drinking too much alcohol, lack of exercise, being overweight and consuming increased salt in the diet, can raise blood pressure, it has long been established that high blood pressure runs in families. This suggests that alterations within genes may predispose individuals to getting raised blood pressure.

In work published on Sunday 10 May 2009, in Nature Genetics, scientists scanned the entire human genetic code, looking for variation affecting blood pressure. To do this the researchers from the Global BPgen consortium compared 2.5 million genetic variants from 34,433 people of European ancestry with measurements of their blood pressure. This enabled the discovery of eight genetic differences that related to slightly higher, or slightly lower blood pressure. To confirm these were real findings they checked the same regions in up to 90,000 additional white European individuals and 12,000 people of South Indian Asian descent. The group also compared results to those of a second paper from the CHARGE consortium published simultaneously.

The researchers note that although the effect of each variant is modest (1 to 0.5 mm Hg) their combined influence could be sufficient to change the population's risk of stroke or heart attack. They say their findings will help understand the underlying causes of high blood pressure and, in the future, may point to new ways of treating the condition.

Further research is needed to clarify exactly how these genetic differences influence blood pressure but the researchers suspect that some of the genes involved may control the production of chemicals, known as steroids, which affect how the kidneys process salt, others may influence how the blood vessels regulate blood pressure. Many of the regions would not ever have been suspected from our current knowledge of blood pressure.

The research involved a number of investigators from Imperial College London, who contributed analyses across the whole genome, as well as follow-up (replication) data of identified genetic variants in people of both European and Indian Asian descent.

High blood pressure is a major risk factor for heart disease and stroke

Professor Paul Elliott, the Head of the Department of Epidemiology and Public Health at Imperial, who is one of the lead investigators of the study, said: "Raised blood pressure is one of the leading causes of death and disability worldwide, contributing to an estimated 4 million extra deaths in developing countries and 3 million extra deaths in developed countries per year. This study, based on analysis of blood pressure and over 2 million genetic variants in thousands of people in Europe and USA, has identified common genetic variants not previously known to be associated with blood pressure levels.

"The results give new clues as to possible mechanisms underlying the development of high blood pressure. These new genetic findings add to existing knowledge of established lifestyle modifications known to improve blood pressure levels, such as reduced salt intake, weight reduction, moderation of alcohol intake and increased exercise," added Professor Elliott.

Dr. Christopher Newton-Cheh (Massachsetts General Hospital), Professors Patricia Munroe and Mark Caulfield (Barts and the London School of Medicine and Dentistry) and Dr. Goncalo Abeçasis (University of Michigan) co-led the research.

-Ends-

Notes to editors:

Blood pressure is a combination of two measurements – the highest point, known as the systolic blood pressure, reflects the pressure at which blood is expelled from the heart. Every time the heart expels blood it must rest and fill again. During this time we record a second reading, the diastolic blood pressure, this more closely reflects how narrow the blood vessels are in the circulation. A normal measurement should be below 120/80 mmHg (millimetres of mercury).

The World Health Organisation define high blood pressure as readings sustained on several occasions above 140/90 mm Hg. Although there are multiple therapies for blood pressure lowering only about 50% of those treated attain recommended targets. In spite of multiple therapies a high proportion of patients remain uncontrolled and approximately 20% are resistant or do not respond to multiple treatments.

Further work is needed to define the precise mechanisms by which these genes influence blood pressure. At this time there is no case for genetic testing.