<prompt> A patient presenting with cutaneous vasculitis, glomerulonephritis, and peripheral neuropathy. Which investigation is to be performed next that will help you diagnose the condition?ANCARA factorHbsAgMIF  <response>: A ANCA ?ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES ANCA:oANCA are antibodies directed against certain proteins in the cytoplasmic granules of neutrophils monocytes.oAs in the given question case history:-ANCA are present in a High percentage of patients with active granulomatosis with Polyangiitis Wegeners Microscopic Polyangiitis.-ANCA present with a Lower percentage of patients with Eosinophilic Granulomatosis with Polyangiitis Churg- Strauss.oThese diseases share the presence of ANCA small-vessel vasculitis, some investigators have come to refer to them collectively as ANCA-associated vasculitis.APPLICATIONS OF ANCAPrevalence of ANCA in renal vasculitisType of renal vasculitisANCA test positivity P-ANCAC-ANCA. Polyarteritis nodosa10-2010-20. Microscopic polyangitis50-8010-20. Wegeners granulomatosis10-2080-90. Necrotizing crescentic GN50-8010-20 pANCA disease associationcANCA disease: associationAtypical. Primary vasculitis. Microscopic polyangiitis. Churg-Strauss syndrome. Polyarteritis nodosa. Collagenosis. Feltys syndrome. SLE. Rheumatoid arthritis. Sjogrens syndrome. Chronic inflammatory bowel disease. Chronic liver disease. Primary sclerosing cholangitis. Primary vasculitis. Wegeners granulomatosis. Microscopic polyangiitis. Churg-Strauss syndrome. Primary sclerosing cholangitis. Primary biliary cirrhosis. Autoimmune hepatitis. SLE. RA ANCA ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODY-ASSOCIATED VASCULITIS AAVDefining featuresClinical RelevanceCHCC 2012 definitions of AAVEvidence that ANCAs are pathogenicGPA:. Granulomatous inflammation usually involving the respiratory tract. Small-vessel necrotizing vasculitis. Necrotizing glomerulonephritis is commonMPA:. Small-vessel necrotizing vasculitis. Necrotizing glomerulonephritis is very common. Pulmonary capillaries often occursEGPA:. Eosinophil-rich granulomatous inflammation of the respiratory tract. Small-vessel necrotizing vasculitis. Blood eosinophlia. AsthmaClinical evidence:. Strong association with ANCA MPA 90, GPA 90, EGPA 40. Partial correlation of ANCA titre with disease activity. Correlation of ANCA epitope specificity with disease activity MPO-ANCA only. Disease indication by trans-placental transfer of ANCA one MPO-ANCA case report. Similar disease associated drug-induced ANCA. HLA genetic associations with MPO-ANCA and PR3-ANCA-assocated disease. Response to immunosuppressive therapy that targets B cellsIn vitro evidence:. Activation of cytokine-primed neutrophils by ANCA IgG. Endothelial injury by ANCA-activated neutrophils. Alternative complement pathway activation by ANCA-activated neutrophilsEvidence from animal models:. Induction of pauci-immune vasculitis, glomerulonephritis and graunolomatosis in mice and rats by anti-MPO IgG. Prevention of murine anti-MPO IgG induced disease by blockade of alternative complement pathway activation or blockade of C8a receptor 