[PI*S and PI*Z alpha 1-antitrypsin deficiency: estimated prevalence and number of deficient subjects in Spain].

Background And Objective: Alpha-1-antitrypsin deficiency (AATD) is an hereditary disorder with increased risk of pulmonary emphysema and chronic liver diseases in children and adults. Since it is possible currently in Spain to apply alpha-1-antitrypsin replacement therapy to AATD patients, the objective of this study was to calculate the total number of subjects affected by PIS and PIZ AATD, and its phenotypic distribution. SUBJECTS, MATERIAL AND METHOD: Selection of published studies on allelic frequencies PIS and PIZ according to the following criteria: a) alpha-1-antitrypsin phenotyping performed by isoelectrofocusing; b) rejection of "screening studies"; c) statistic precision factor score of 5, and d) samples representative of the Spanish general population.

Results: Four out 34 cohorts were selected. Mean gene frequencies (per 1,000) were: 104 (95% confidence interval [CI], 96-113) for PI*S and 17 (95% CI, 14-21) for PI*Z. These data indicated that it would exist in Spain 9,173,181 AATD subjects (95% CI, 9,167,966-9,178,398), with the following phenotypic distribution: 7,358,263 (95% CI, 6,696,222-8, 072,328) for PIMS; 1,222,041 (95% CI, 972,767-1,539,805) for PIMZ; 436,023 (95% CI, 369,057-514,244) for PISS; 144,827 (95% CI, 107,227-195,038) for PISZ; and 12,026 (95% CI, 7,788-18,493) for PIZZ. The global prevalence was 1 out of 4.4 individuals, with the following distribution: PIMS 1/5; PIMZ 1/33; PISS 1/92; PISZ 1/278; and PIZZ 1/3,344.

Conclusions: AATD is a frequent but underdiagnosed disease in Spain.