Alpha-1-antitrypsin PI phenotypes S and Z in Europe:: an analysis of the published surveys

The objective of the present study was to review published surveys on allelic frequencies S and Z in European populations to evaluate the validity of the reported data. More than a hundred studies on the topic, published since 1965 until 2000, were retrieved by Medline, Index Medicus and bibliographic references consultation. The criteria for studies selection were: 1) sample size greater than or equal to 250 individuals, 2) alpha-1-antitrypsin phenotype determination performed by means of crossed antigen-antibody or isoelectric focusing in polyacrylamide gels; 3) PI type determination performed without any previous screening procedure; 4) S and Z 95% confidence interval (CI) of the reported outcomes with a calculated coefficient of variation < 42.3 for S and < 95.8 for Z; 5) S and Z 95% CI of the reported outcomes comprised within 95% CI limits of comparative hypothetical surveys designed with the same sample size of the questioned surveys and the highest/lowest frequencies accepted for a specific area, according to the figures of isogen boundary maps. Seventy studies comply with the five established criteria for analysis. According to the data of the selected studies, a geographical distribution on S and Z gene frequencies in Europe is proposed.