Which test marker is associated with Wegner's granulomatosis?

Wegener's granulomatosis, now referred to as granulomatosis with polyangiitis, is a type of vasculitis associated with the presence of anti-neutrophil cytoplasmic antibodies (ANCA). Specifically, the test marker most commonly associated with this condition is C-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies). C-ANCA is directed against a protein called proteinase 3 (PR3), which is found in neutrophils. The presence of these antibodies is a significant diagnostic criterion and is often used to confirm the diagnosis of granulomatosis with polyangiitis.

In summary, the association of C-ANCA with Wegener's granulomatosis is prominent because these antibodies reflect the underlying pathophysiological process of the disease, which involves inflammation of blood vessels leading to granuloma formation in various organs, particularly the respiratory tract and kidneys.