Systemic Lupus Erythematosus - Causes

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Autoantibodies. In the majority of patients with SLE, antinuclear antibodies (ANA) are detectable. Important research published in 2003 found that such autoantibodies may be present in individuals up to 7 years prior to their developing symptoms of lupus. Some subtypes of ANA are found in lupus patients and only rarely in people without lupus. These include:

• Anti-ds DNA. An autoantibody called anti-double stranded DNA (anti-ds DNA) may play an important role in some lupus patients. A 2001 study suggested that some of these antibodies specifically recognize a protein in the kidney called alpha-actinin, which researchers suspect may also occur in other tissues that are affected by SLE, such as in the skin, joints, and brain. A subset of anti-DNA has also been found to target nerve-cell receptors in the brains of patients with SLE.
• Anti-Sm antibodies. This antibody is found most often in lupus patients of African descent and is almost never detected in people without lupus. Although the antibody is not usually seen in lupus patients, its confirmed presence almost always indicates SLE.

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Other autoantibodies found in lupus patients include:

• Anti-Ro (SSA) and Anti-La (SSB). These autoantibodies may be involved in the sun-sensitive rashes experienced by patients with SLE and are also found in association with neonatal lupus syndrome, in which a pregnant mother's antibodies cross the placenta and cause inflammation in the developing child's skin or heart.
• Antiphospholipid antibodies. A quarter to a half of patients with SLE may have these antibodies. They attack blood clotting regulator proteins which stick to phospholipids, fatty compounds found in cell membranes throughout the body. Antiphospholipid antibodies increase the risks for blood clots and may be responsible for narrowing of and irregularities in blood vessels. Antiphospholipid antibodies are linked with miscarriages and other pregnancy complications, strokes, heart attacks and blood clots in almost any part of the body, including kidneys, legs, lungs, and eyes.