Heart disease is the largest killer in America today. According to the Heart, Lung and Blood Institute, more than a million Americans have a heart attack each year, and half a million die from heart disease. Cholesterol plays a major role in heart disease, and the synthesis of cholesterol within the body is in part due to our heredity, so the risk of death from heart disease is partly predicated by genetics.
Cholesterol
Cholesterol is a type of waxy lipid used as a structural component in cell membranes and is a precursor molecule to certain hormones, according to the University of Cincinnati-Clermont College. It is packaged and transported in the blood by a molecule known as a lipoprotein. Too much cholesterol in the bloodstream, however, can build up in the artery walls and narrow the flow of blood. This is why cholesterol is one of the major risk factors for heart disease.
Causes
There are many different causes of blood cholesterol, but only about 15 percent of it is actually the product of dietary cholesterol intake, says the University of Cincinnati. The rest is manufactured by the body. Smoking, physical activity and saturated fat consumption all play a role. But genetics is also one of the factors that guide the rate at which blood cholesterol is produced.
Genetics
DNA contains the code that produces protein in the body. Proteins are important because they facilitate chemical reactions. This is the basis for our metabolism, the set of all reactions in the body. The parts of our cells that are responsible for lipid metabolism are ultimately the parts where blood cholesterol is metabolized. Because people have slightly different DNA, it can also be expected that metabolism of blood cholesterol diverges from person to person.
Significance
According to Dr. Robert H. Eckel, professor of medicine at the University of Colorado School of Medicine, genes cause a large variability to the amount that cholesterol levels change from person to person in response to different risk factors. Genes can even be used to predict how well people would respond to restrictions on dietary cholesterol and saturated fat and other lifestyle risk factors. Within the next few decades there may even be genetic profiles that allow physicians to predict the outcome of blood cholesterol based on these externalities.
Considerations
Unfortunately, the link between genotypes and phenotypes---in other words, the link between our genes and our characteristics and behavior---tends to be very complex. Traits are usually caused by multiple genes or regions of the DNA. A team of researchers led by the University of Michigan School of Public Health identified 95 different regions of the human genome where genetic variants are associated with blood cholesterol and triglyceride levels. These regions are also associated with lipid metabolism.
