Genetic study of Tunisian Berbers. II. Alpha 1-antitrypsin (Pi) polymorphism: report of a new allele (Pi S Berber).

The alpha 1-antitrypsin (alpha 1-AT) (Pi) polymorphism has been studied in three Berber groups of Tunisia by high-resolution isoelectric focusing. The results showed that actual Tunisian Berbers are mainly Caucasoid. A new variant of alpha 1-AT, tentatively called Pi S Berber, was found in the three Berber groups. On isoelectric focusing this variant was slightly more cathodal than the product of the usual Pi S allele. Family studies showed that the Gm-Pi linkage is probably close when the Pi locus supports the Pi P allele which is responsible for moderate (30%) serum alpha 1-AT deficiency.