Screen search for siblings

MORE THAN 1,500 sets of brothers and sisters are being enlisted across the United Kingdom in a bid to discover the genes responsible for high blood pressure.

Researchers at Aberdeen, Cambridge, Glasgow, Leicester, London and Oxford universities are working together on the five-year project, backed by Pounds 2.15 million from the Medical Research Council. Support has also come from the British Hypertension Society and the British Heart Foundation.

The project is known as BriGHT, which stands for British Genetics of Hypertension, but also commemorates the Edinburgh-trained London physician John Bright, who in the 1820s produced the first description of kidney disease, which can be caused by high blood pressure.

The disease, which also greatly increases the risk of a stroke or heart attack, is known to result from the link between the patient's lifestyle, environment and hereditary factors.

The study will concentrate on the inherited aspects of the disease, using the general practitioner network to identify families with two or more siblings with high blood pressure.

John Connell of Glasgow's department of medicine and therapeutics, one of the project's coordinators, said siblings shared half their genes from their parents on average. The study would investigate what genes they had in common. Such a large survey should mean certain genes coming through very strongly.

Studying the genetics of common diseases has developed dramatically over the past five years following the advances of the Human Genome Project, Professor Connell said.

The United Kingdom study would be on a comparable scale to research in the United States and continental Europe. "But in the US, they have particular problems because of the enormous ethnic and geographical diversity and greater social mobility," he said.

"Britain is probably uniquely placed because of its relatively homogeneous population, its relatively limited geography, and the fact that all patients have a GP who normally looks after blood pressure. That doesn't happen in the US or Europe."

Having six universities involved would mean brothers and sisters who lived in different parts of the country from one another could still be assessed, Professor Connell said.

Each centre will have a clinician involved in day-to-day monitoring and two research nurses who will visit patients, usually in their GP's surgery, to measure blood pressure and take a blood sample. Patients will also be asked to complete a questionnaire covering topics such as diet, smoking and drinking.

Professor Connell stressed that the information gathered would be kept anonymous. "It won't be possible for somebody to say 'Mrs Bloggs in Aberdeen has admitted to drinking 20 pints of lager a week'," he said.

The data will go fortnightly to London where it will be collated by a team in St Bartholomew's Hospital led by Professor Connell's fellow coordinators Mark Caulfield and Nigel Benjamin. The data collection is expected to take three years with another two years to analyse the links between the clinical and genetic data.

The genetic screening will be carried out by a team in Oxford's Wellcome Trust Centre for Human Genetics, led by Mark Lathrop.

In certain rare instances, a single gene may account for a family's predisposition to suffer from high blood pressure, but the researchers believe that the cause will more often be the interaction of several genes, with five already suspected of playing a part in the disease.

"Information from this study will help us understand the inherited factors which lead to high blood pressure, particularly those which which interact with the patient's own environment," Professor Connell said. The researchers hope the study's findings will lead to people at risk being identified early in life, with better targeting of prevention and treatment. Estimates suggest that between 10 and 20 per cent of the population suffer from the disease, rising to between 40 and 50 per cent among the over 60s.

Anyone interested in taking part in the study should contact Janine Pembroke on 0171 415 3422.