Scientists have found that a common gene variant, when carried by cigarette smokers, can significantly increase the risk of coronary heart disease - Britain's single biggest killer.
The new research, funded by the British Heart Foundation (BHF), comes from a collaboration between University College London and the Wolfson Institute at St Bartholemew's Hospital published in THE LANCET today.
While smokers have an increased risk of coronary heart disease (CHD), this new research reveals that some smokers have a significantly higher risk than others. Genetic factors have long been known to be important in determining risk of heart disease, but it is only recently that scientists have been able to identify the particular genes involved. Researchers focused on the Apo-E gene known to be important in controlling the levels of fat in the blood. The gene comes in three common forms - E2,E3 and E4.
The researchers took a group of 3,052 healthy middle aged men (50 to 61 years) drawn from general practices throughout the UK. Participants in the study had their cholesterol and other heart disease risk factors measured as well as completing a smoking questionnaire. Current smokers were defined as 'having smoked at least one cigarette per day for at least one year.' All others were classified as ex or never smokers.
DNA based techniques were used to determine if the men carried one or more copies of the E2 or E4 variant or held the common E3 version. The participants were then monitored annually for an 8 year period. CHD events included all fatal or non-fatal heart attacks plus any coronary artery surgery and silent heart attack - identified by ECG - occurring over the period of the study.
As expected there was a strong association between smoking and risk of coronary heart disease. For every year of the study the CHD events were 5.1 per 1,000 in never smokers and 7.5 per 1,000 in ex-smokers.