[[Alpha].sub.1] Antitrypsin phenotypic variability is not associated with ANCA in southern Chinese.(antineutrophil cytoplasmic antibody)

[[Alpha].sub.1] Antitrypsin ([[Alpha].sub.1],AT) is a 52 kDa proteinase encoded by a gene locus Pi on chromosomal segment 14q32.1. It is a natural inhibitor of proteinase 3 (PR3), a neutrophil granular protein and a major autoantigen of antineutrophil cytoplasmic antibody (ANCA). The function of [[Alpha].sub.1],AT is in turn restricted by myeloperoxidase (MPO), another autoantigen of ANCA. The interplay between the enzymes, inhibitors, and the autoantibodies is implicated in the dynamics of the vasculitic process,[1] resulting in a whole spectrum of clinical conditions ranging from systemic granulomatous diseases to kidney limited glomerulonephritis. There have been reports of the correlation of specific [[Alpha].sub.1]AT alleles, notably [Pi.sup.z], with ANCA.[2-4] These were largely studies of white subjects, which may not necessarily be extrapolated to all populations.

[[Alpha].sub.1]AT variant phenotypes may have predisposed to PR3-ANCA, but the same association may not exist for MPO-ANCA. In populations with a low prevalence of [[Alpha].sub.1]AT variant phenotypes, the pattern of ANCA could differ from …