A new, high frequency variant of alpha1-antitrypsin.

A new variant of alpha1-antitrypsin has been detected with the aid of isoelectric focusing on polyacrylamide slab gels. In contrast with many other variants this new alpha1-antitrypsin allele is found in 10-15% of the phenotypes examined. The electrophoretic properties of the new alpha1-antitrypsin variant in isofocusing polyacrylamide gels differ only slightly from the most common alpha1-antitrypsin allele M. On the basis of its electroforetic behaviour we propose the term MN to indicate this new protease inhibitor variant. The isofocusing technique employed, provides an easy to handle, very reproducible method for determining the alpha1-antitrypsin phenotype and can be employed for large scale screening.