Alpha 1-antitrypsin (pi) phenotypes in a village population from The Gambia, West Africa. Evidence of a new variant occurring at a polymorphic frequency.

A total of 701 individuals from a village in The Gambia, West Africa were tested for serum alpha 1-antitrypsin phenotypes by isoelectric focusing in thinlayer polyacrylamide gels (pH 4--5). A new variant allele, PiGAM, was discovered at a polymorphic frequency (0.0642), and the inheritance of the variant phenotype was confirmed by family studies. The variant was not found to be associated with any decrease in serum alpha 1-antitrypsin concentration. The only other allele found within this population was the common allele PiM (0.9358).