Polymorphism of alpha-1 antitrypsin in dogs

1. A genetically determined polymorphism of alpha-1 antitrypsin is demonstrated in dog serum by isoelectric focusing in a pH range of 3.5-5.0, followed by direct immunoblotting using a specific antiserum. 2. Alpha 1 antitrypsin focuses as two major bands at isoelectric points of 4.60 and 4.64 or 4.67 and 4.7 in presumed homozygous animals. Heterozygotes show both sets of bands. 3. The results of seven crosses with 33 offspring are best explained by two codominant alleles, PiM and PiS at a single locus designated as Pi for proteinase inhibitor. 4. The concentration of alpha-1 antitrypsin in serum of healthy dogs was 2.65 +/- 0.42 mg/ml and 2.19 +/- 0.38 mg/ml in females and males respectively. 5. The higher concentration in female dogs suggests that estrogens may influence the serum level of alpha-1 antitrypsin.