Two groups of 708 healthy blood donors and 563 patients affected with chronic obstructive lung disease (C.O.L.D.) respectively, have been screened for al-antitrypsin (alAT) variants by electrophoresis on agarose-polyacrylamide gels at pH 4.7 and isoelectric focusing (IEF).
The frequencies of the Pi (Protease inhibitor) alleles are comparable to those observed in the North European populations. As expected, the frequency of the Z gene is higher in the group of patients with C.O.L.D. Also the frequency of MZ phenotypes is higher among these patients, but in this case the difference is not statistically significant.
With the aid of the electrophoretic methods described in the text we were able to detect a new electrophoretic variant (M3) showing a mobility intermediate between the M1 and the M2 phenotypes. * Address offprint requests to: Instituut voor Anthropogenetica Wassenaarseweg 72, Leiden, The Netherlands 1 Before any final decision is taken by the International Pi committee, we indicate the common Pi allele as 'MI' and the other two alleles described in this paper as M2 and M3. This decision is in agreement with the opinion of many participants to a discussion on Pi nomenclature held in Mexico City at the Vth International Congress of Human Genetics. Whenever in the text the notation 'M' appears without further indications, it includes Ml as well as M2 and M3.