<prompt> A patient Complains of hematuria. Renal biopsy demonstrates a focal necrotizing glomerulonephritis with crescent formation. He also complains of decreased sensation in hand and feet .What next best investigation should be done to diagnose the condition?MIFHbsAgRA factorANCA  <response>: Patient is suffering from vasculitis due to which he is manifesting symptoms of haematuria , periphral neuropathy and glomerulopnephritis ,and next investigation should be ANCA to narrow down specific cause. Antineutrophil cytoplasmic antibodies ANCA The antibodies are of two types, anti-proteinase 3 PR3 or anti-myeloperoxidase MPO ANCA are produced with the help of T cells and activate leukocytes and monocytes, which together damage the walls of small vessels. ANCA antibodies are directed against cell constituents because of which circulating immune complexes are not present. c - ANCA p- ANCA Anti-proteinase 3 Anti-myeloperoxidase Granulomatosis with polyangiitis Wegener granulomatosis Microscopic polyangiitis and Churg-Strauss syndrome Cytoplasmic staining Perinuclear staining FIG: 1. C-ANCA, 2. P-ANCA-staining patterns on alcohol-fixed human neutrophils. 