September 3, 2015
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Systemic Lupus (cont.)

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What causes systemic lupus erythematosus? What are risk factors for lupus? Is lupus hereditary?

The precise reason for the abnormal autoimmunity that causes lupus is not known. Inherited genes, viruses, ultraviolet light, and certain medications may all play some role. Lupus is not contagious.

Genetic factors increase the tendency of developing autoimmune diseases, and autoimmune diseases such as lupus, rheumatoid arthritis, and autoimmune thyroid disorders are more common among relatives of people with lupus than the general population. Moreover, it is possible to have more than one autoimmune disease in the same individual. Therefore, "overlap" syndromes of lupus and rheumatoid arthritis, or lupus and scleroderma, etc., can occur.

Some scientists believe that the immune system in lupus is more easily stimulated by external factors like viruses or ultraviolet light. Sometimes, symptoms of lupus can be precipitated or aggravated by only a brief period of sun exposure.

It also is known that some women with SLE can experience worsening of their symptoms prior to their menstrual periods. This phenomenon, together with the female predominance of SLE, suggests that female hormones play an important role in the expression of SLE. This hormonal relationship is an active area of ongoing study by scientists.

Research has demonstrated evidence that a key enzyme's failure to dispose of dying cells may contribute the development of SLE. The enzyme, DNase1, normally eliminates what is called "garbage DNA" and other cellular debris by chopping them into tiny fragments for easier disposal. Researchers turned off the DNase1 gene in mice. The mice appeared healthy at birth, but after six to eight months, the majority of mice without DNase1 showed signs of SLE. Thus, a genetic mutation in a gene that could disrupt the body's cellular waste disposal may be involved in the initiation of SLE.

What is drug-induced lupus?

Dozens of medications have been reported to trigger SLE. However, more than 90% of cases of "drug-induced lupus" occurs as a side effect of one of the following six drugs: hydralazine (Apresoline) is used for high blood pressure; quinidine (Quinidine Gluconate, Quinidine Sulfate) and procainamide (Pronestyl; Procan-SR; Procanbid) are used for abnormal heart rhythms; phenytoin (Dilantin) is used for epilepsy; isoniazid (Nydrazid, Laniazid) is used for tuberculosis; and d-penicillamine (used for rheumatoid arthritis). These drugs are known to sometimes stimulate the immune system and cause SLE. Fortunately, drug-induced SLE is infrequent (accounting for less than 5% of all people with SLE), and it usually resolves when the medications are discontinued.

Medically Reviewed by a Doctor on 3/5/2015

Source: MedicineNet.com
http://www.medicinenet.com/systemic_lupus/article.htm

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