Increased frequency of the MZ phenotype of alpha-1-protease inhibitor in juvenile chronic polyarthritis.

Pi phenotypes of alpha-1-protease inhibitor were determined by isoelectric focusing and print immunofixation in 96 English children suffering from juvenile chronic polyarthritis. A significantly increased frequency of the MZ phenotype (10.41%) was found in comparison with a geographically matched control population (1.6%). The results of this study suggest that the possession of a Z-deficient allele of alpha-1-protease inhibitor could be a predisposing, aggravating, or perpetuating factor in the articular damage occurring in juvenile chronic polyarthritis.