Objective: To determine serum level of the protease inhibitor, to identify phenotypes and determine their frequencies.

Study Design: A prospective study.

Setting: PMRC Research Centre, JPMC and the Aga Khan University Hospital Karachi.

Subjects: Healthy aduIts without history ol peptic ulcer disease and a normal endoscopy.

Methodology: Quantitive measurement of serum alpha 1 AT was carried out by radial immunodiffusion. phenotyping by iso-electric focusing and confirmation of phenotypes by immunofixation and DNA analysis technique.

Results:Serum alpha I AT was low in 13.4% of the subjects. Ni MM phenotype predominated followed by SZ SS, MZ and ZZ. DNA diagnosis accurately resolved the phenotypes as S and Z.

Conclusion: Frequency by phenotype associated with total and intermediate deficiency is less in the population