ATM and systemic sclerosis: The three commonest hallmark autoantibodies in SSc (found in 60%–80% of patients)include anti-topoisomerase antibody (ATA, anti-Scl-70), anti-RNA polymerase IIIantibody (ARA), both found more frequently in diffuse cutaneous SSc (dcSSc) (20%–30%of SSc patients, (85% dcSSc) and 10%–20% of SSc patients (> 80% dcSSc),respectively), and anti-centromere antibody (ACA), found in up to 40% of patients(95% of them being classed as limited cutaneous SSc (lcSSc)).8,9