PiMheerlen, alpha PiM allele resulting in very low alpha 1-antitrypsin serum levels.

A patient with pulmonary emphysema is described, who had a very low alpha 1-antitrypsin serum concentration (2% of normal). After isoelectric focusing and staining, the patient's serum revealed no visible alpha 1-antitrypsin bands. Immunofixation, following isoelectric focusing, gave a banding pattern identical to that of a normal M type. The existence of this deficient M-allele was confirmed by family studies. Low alpha 1-antitrypsin concentrations, due to the presence of the deficient allele, were coupled with low serum antitrypsin activities.