A 30 year old lady presents to the outpatient department with an erythematous butterfly rash on her cheeks. Which of the following antibodies should be assayed initially for her suspected condition:

Ans. (a) Anti-ds-DNA(Ref: Robbins 9th/pg 218-221)The given clinical features are suggestive of SLE;Specific test for diagnosis of SLE is anti ds DNA;This antibody also correlates with disease activity, nephritis, vasculitis.So Anti-dsDNA should be initially assayed in this case.