Specificity obtained with disease controls. According to Damoiseaux et al. (12). IIF - indirect immunofluorescence. ANCA - antineutrophil cytoplasmic antibodies. C-ANCA - cytoplasmic antineutrophil cytoplasmic antibodies. P-ANCA - perinuclear antineutrophil cytoplasmic antibodies. PR3 - proteinase 3. MPO – myeloperoxidase. Se - sensitivity. Sp - specificity. GPA - granulomatosis with polyangiitis. MPA - microscopic polyangiitis. The gene discussed is MPO; the disease is microscopic polyangiitis.