<prompt> A lady when exposed to Cold, Extremities turn to blue. Which of the following antibody is associated with it?Anti SCL-70Anti ROAnti SS-AAnti SS-B  <response>: The above scenario is described as Raynauds phenomenon, which is seen in Scleroderma. Raynauds phenomenon Fibrosis of skin around digital blood vessels On Cold exposure due to abnormal vasoconstriction Tip of fingers turns white. Antinuclear antibody ANA is the most sensitive antibody in scleroderma and is the preferred screening test. Anti-centromere antibody is most specific for CREST syndrome. Anti-topoisomerase I Scl-70is most specific fordiffuse systemic sclerosisdiffused Scleroderma. 