Scleroderma Antibody Test

Scleroderma Antibody (Scl-70) refers to an autoantibody that mistakenly targets one of the body’s own nuclear enzymes, called DNA topoisomerase I. This enzyme plays a critical role in managing the structure of DNA during essential processes like replication and transcription, meaning it helps the DNA unwind and rewind as needed for cells to function properly. When the immune system creates antibodies against topoisomerase I, it disrupts normal cellular activity and contributes to the widespread fibrosis—or thickening and scarring—of skin and internal organs that defines systemic sclerosis, commonly known as scleroderma.

Scleroderma itself comes in two main types: limited cutaneous and diffuse cutaneous. Scl-70 antibodies are most strongly associated with the diffuse form, which tends to progress more rapidly and severely, affecting not just the skin but also major organs like the lungs and heart. In fact, studies show that Scl-70 antibodies are present in up to 77% of people with diffuse scleroderma. They are much less common (10–18%) in the more localized, milder form called CREST syndrome (an acronym for Calcinosis, Raynaud’s phenomenon, Esophageal dysfunction, Sclerodactyly, and Telangiectasia).

When a patient tests positive for Scl-70 antibodies, it suggests a higher risk for complications such as pulmonary fibrosis (scarring of the lungs), renal crisis, and greater overall mortality compared to patients without these antibodies. It is important to note, however, that the presence of Scl-70 does not guarantee that these complications will occur—it is simply a marker of increased risk.