Patient presenting with cutaneous vasculitis, glomerulonephritis, peripheral neuropathy, which of the following will help in diagnosis?

Ref. API Textbook of Medicine. Pg. 1313   Cutaneous vasculitis features – Diagnosis Anti-neutrophil cytoplasmic antibodies (ANCAs): Group of autoantibodies IgG type mainly, Produced against antigens in cytoplasm of neutrophil granulocytes & monocytes. Particularly associated with systemic vasculitis, so called “ANCA-associated vasculitis”. c-ANCA – Abs against MPO, p-ANCA -  Abs Against PR3