What Causes Lupus?

Lupus is an autoimmune disorder, which means the body's immune system attacks its own healthy cells and tissues. Lupus is considered to be a multifactorial condition. Multifactorial inheritance means that many factors are involved in causing a health problem. The factors are usually both genetic and environmental, where a combination of genes from both parents, in addition to unknown environmental factors, produce the trait or condition.

Often one gender (either males or females) is affected more frequently than the other in multifactorial traits. Multifactorial traits do recur in families because they are partly caused by genes. Females are affected with lupus three to ten times more often than males.

A group of genes on chromosome 6 codes for the HLA (human leukocyte antigens) antigens which play a major role in susceptibility and resistance to disease. Specific HLA antigens influence the development of many common disorders, many that are autoimmune related and are inherited as multifactorial traits.

When a person has the specific HLA antigen type associated with the disease, they may have a genetic susceptibility to have the condition and be more apt to develop it. The HLA antigen associated with lupus is called DR2 and DR3. It is important to understand that a person without these antigens may also develop lupus, so that HLA antigen testing is not diagnostic or accurate for prediction of the condition.

What is the immune system?

The purpose of the immune system is to keep infectious microorganisms, such as certain bacteria, viruses, and fungi, out of the body, and to destroy any infectious microorganisms that do invade the body. The immune system is made up of a complex and vital network of cells and organs that protect the body from infection.

When the immune system does not function properly, a number of diseases can occur. Allergies and hypersensitivity to certain substances are considered immune system disorders. In addition, the immune system plays a role in the rejection process of transplanted organs or tissue.

Other examples of immune disorders include the following:

• Autoimmune diseases, such as juvenile diabetes, rheumatoid arthritis, and anemia
• Immunodeficiency diseases, such as acquired immunodeficiency syndrome (AIDS) and severe combined immunodeficiency (SCID)