The PiZ gene of α1-antitrypsin as a determinant of outcome in PR3-ANCA-positive vasculitis

The PiZ-gene of α 1 -antitrypsin as a determinant of the outcome in PR3-ANCA-positive vasculitis. We have previously demonstrated that a strong correlation exists between systemic vasculitis with proteinase 3-anti-neutrophil cytoplasm antibodies (PR3-ANCA) and heterozygosity for α 1 -antitrypsin (α 1 -AT) deficiency, PiZ. In the present study we characterized the PiZ-positive subgroup by laboratory findings, clinical features and outcome. The series studied consisted of 18 PiZ-positive and 81 PiZ-negative PR3-ANCA patients, comparable in sex ratio, age, C-reactive protein concentrations and renal function at diagnosis, and treatment. PiZ-positive patients had a more disseminated disease as reflected by the number of affected organs (P 1 -AT seen in PiZ-heterozygotes enhances the risk of dissemination of the vasculitic process and the risk of a fatal outcome. We consider α 1 -AT phenotyping to be justified in cases of PR3-ANCA-positive vasculitis. Treatments decreasing plasma α 1 -AT (such as plasmapheresis without plasma replacement) may be deleterious.