Smokers with a version of a gene linked to high cholesterol levels have a higher risk of developing heart disease, scientists say in a study released today.
Smokers are more likely to suffer from heart disease than nonsmokers, but scientists at Imperial College and St. Bartholemew’s Hospital in London have discovered that a certain form of a gene may be responsible for that risk.
“We identified a particular variant of the ApoE gene that increases the risk of coronary heart disease, but only if you are a smoker,” said Professor Steve Humphries of Imperial College.
ApoE plays an important role in controlling cholesterol levels in the blood.
It affects both low-density lipoprotein, or bad cholesterol, which builds up on artery walls, and high-density lipoprotein, or good cholesterol, which carries the deposits away.
People inherit one of three types of the gene – E2, E3 or E4.
ApoE3 is the most common variation, but many people have at least one copy of ApoE4.
Humphries found that variant is particularly bad for smokers.
“What is clear from our research is that having the E4 version of the ApoE gene increases the risk of coronary heart disease in smokers by about three times,” the scientist said.
During an eight-year study, published in the latest edition of The Lancet medical journal, Humphries and his colleagues followed more than 3,000 men aged 50 to 61.
They recorded their cholesterol levels, smoking habits and “coronary events,” such as angina and heart attacks. They also used DNA tests to determine which copies of the ApoE gene each had.
Not surprisingly, they found that smokers had more than double the risk of heart problems than nonsmokers.