The study of human health reveals that there are a group of diseases that are clearly genetic in origin, caused by defective genes or chromosomes; many of these disorders, such as the muscular dystrophies, present early in life and, unless specific therapies are available, significantly decrease that individual's expected life span.
A host of other diseases also have been recognized to "run in families," indicating that affected individuals have a genetic predisposition to that condition; cardiovascular disease is included in this group. While the inherited factors increase the risk for these health disorders, that risk may be diminished by lifestyle choices that are known to counter the development of the pathologic process (e.g. engaging in regular aerobic exercise and avoiding tobacco use in the case of cardiovascular disease).
While we often assume that common infections affect everyone equally, it has become evident that one's immune health is closely linked to genetics and that any given individual may be more or less susceptible to specific infectious agents and/or to the complications of those infections; complications may include conditions such as autoimmune disease, certain malignancies and multiple sclerosis, among many others. In like manner, our genes also govern our relative sensitivity to a wide variety of toxic agents, including alcohol, tobacco and environmental carcinogens. In the end, our genome is the most important determinant of our overall health while preventive measures and the availability of therapeutic intervention play secondary though vital roles.
