Determination of alpha-1-antitrypsin phenotypes and M subtypes by isoelectric focusing in immobilized pH gradients.

A procedure to determine alpha-1-antitrypsin phenotypes (Pi types), including the six common PiM subtypes, is described. Phenotypes of the inhibitor, including the deficiency phenotype PiZ and the PiM subtypes, can be identified by isoelectric focusing in an immobilized pH gradient with a pH range of 4.2 to 5.0 or 4.0 to 5.0. This method gives clear separation of M, S, V, P and Z allele products. Up to 24 samples can be analyzed in a single overnight run using commercially available equipment and reagents.