What is Genetics? : What is a complex disease?

What is a complex disease?

Nearly all disease has a genetic component!

Some diseases have a stronger genetic component than others. But, most common diseases like heart disease, diabetes, and cancer do not follow a certain inheritance pattern. This is because those diseases are likely caused not only by changes in our genes, but by our environment, lifestyle, age and diet, among many other things.

Depending on the disease, the genetic component may be large or may be very small. For example, a disease with a large genetic component is sickle cell anemia. A person with sickle cell anemia has a genetic mutation that causes their red blood cells to change shape (sickle), causing severe pain, anemia and organ damage. Sickle cell disease is caused almost completely by genetics. However, there is a small environmental component that may cause the disease to be more or less severe. On the opposite end of the spectrum, there are diseases that are almost completely caused by environment (lifestyle, diet, exercise, drug use, etc.). An example of this is HIV/AIDS. Although there are genes that can increase or decrease the risk of a person catching the virus, AIDS is caused by environmental factors (exposure to someone else who has HIV).

Complex diseases are diseases that are caused in large part by genes AND environmental factors. Since complex diseases do have a genetic component, they can be seen running through a family, but the pattern may not be very clear. There are many examples of complex disease: Alzheimer disease, autism, heart disease, diabetes, multiple sclerosis, Parkinson disease, osteoporosis, glaucoma, depression, arthritis, stroke, cancer.

Research on Complex Diseases

You may have noticed that these complex diseases are extremely common conditions! Most of us have a family history of at least one of these diseases. Because these diseases affect so many people, current efforts in genetic research are focused on finding out the genetic and environmental causes for them. If the genetic cause of complex disease is better understood, the diseases can be prevented, better treated and possibly cured. The John P. Hussman Institute for Human Genomics is a leader in complex disease research. The HIHG conducts genetic research studies to find genes for autism, Alzheimer disease, multiple sclerosis, and many many more! Learn more about the studies going on at the About Us page.

Read on: My Family Health History