The clinical criteria to define MCD were described by the CastlemaB Trial Group,9 and include fever, raised serum CRP (>20 mg/L) in the absence of another cause, and 3 of 12 additional clinical findings (lymphadenopathy, splenomegaly, edema, pleural effusion, ascites, cough, nasal obstruction, xerostomia, rash, neurologic symptoms, jaundice, autoimmune hemolytic anemia). The gene discussed is CRP; the disease is Pleural effusion.