Did you know the APOE gene can affect your risk of cardiovascular disease?
APOE - the heart attack gene
At your annual exam two months ago, your cholesterol levels were through the roof. Your doctor was worried that you may be at high risk for a heart attack. You religiously follow a low-fat diet, and here you are back at the doctor’s office. You’re not feeling much different, but expecting good news nevertheless. The blood tests are back, but the results are not good. Time for more drastic measures, and the doctor prescribes Lipitor. The doctor can only hope that this treatment will be effective, but you wish there was a better way to predict which treatment works best for you.
Cardiovascular disease involves the narrowing or the blocking of blood vessel, leading to chest pain (angina), heart attacks and strokes. Heart attacks and strokes account for over one-quarter of deaths each year in North America. The known disease risk factors are high blood pressure, high cholesterol, smoking, poor diet, physical inactivity, excess weight, age, and genetics. Treatment options include simple diet changes, increased physical activity, and medications to lower cholesterol levels.
The gene with one of the strongest links to cardiovascular health is the APOE gene. APOE encodes the apolipoprotein E protein, which controls the uptake of cholesterol and fats from the bloodstream into the cells. There are three common genetic versions (alleles) of APOE, called APOE e2, APOE e3 and APOE e4. We inherit one copy of APOE from each parent, which means that we each have two copies of this gene. We may inherit two copies of the same allele, or two different alleles.
The e2 allele is associated with lower LDL-cholesterol – the “bad” cholesterol that contributes to blocked arteries. However, this seemingly beneficial allele may not be so beneficial in individuals who inherit two copies of it. The e2/e2 genotype is associated with an increased risk of type III hyperlipoproteinaemia, which is another factor that contributes to heart problems. The e3 allele is the most common allele, and is associated with normal healthy blood cholesterol levels. The e4 allele is the “heart attack” allele, as it is strongly associated with elevated LDL-cholesterol levels, one of the biggest factors linked to an increased risk of coronary heart disease.
Variation in the APOE gene not only influences our cardiovascular health, but also how we respond to different treatment options. Individuals with either two copies of e2, or one copy each of e2 and e3 generally don’t benefit as well from a low-fat diet, but respond well to statins (cholesterol-lowering medication). People with two copies of e4, or one copy each of e3 and e4, may not efficiently respond to statins, but will benefit more from a low-fat diet to lower their cholesterol levels.
Thanks to advances in DNA technologies, you can now determine which alleles of APOE you have inherited. If you have high cholesterol, knowing which alleles of APOE you carry, may help you and your doctor devise a treatment plan that is personalized to your genetics. Even if you don’t have high cholesterol, simply knowing there is an increased risk for cardiovascular disease just might prompt you to make better lifestyle choices to minimize your risk. Take control of your cholesterol, and don’t become one of the 32.4 million heart attacks and strokes worldwide every year.