Anti-Scl-70, also called anti-topoisomerase I, after the type I topoisomerase target is an anti-topoisomerase antibody-type of anti-nuclear autoantibodies, seen mainly in diffuse systemic scleroderma.
Has a sensitivity of 28–70% for diffuse systemic sclerosis, and is seen in 10–18% of cases of the limited form of systemic scleroderma the CREST syndrome.
Anti Scl-70 antibodies are associated with more severe scleroderma disease.
Sclerosis-70 consists of an abbreviation of scleroderma and a 70 kD extractable immunoreactive fragment obtained from the otherwise larger (100–105 kD) target topoisomerase antigen of the antibodies.