PURPOSE: Alpha-1 Antitrypsin (AAT) deficiency is one common lethal genetic cause of emphysema in adults. The World Health Organization (WHO) recommends detection of AAT level in patients with Chronic Obstructive Pulmonary Disease (COPD) and Asthma. The abnormally low plasma concentrations of AAT in individuals predisposes them to elevated risk of early pulmonary emphysema and in some occasions hepatic damage. The PiZZ phenotype is the most frequently associated with low plasma concentrations of AAT.However much of this data comes from fully developed regions such as North America and Europe.
METHODS: To collect AAT phenotype epidemiological data in a target population of COPD patients. We included 64 patients and conduct a detection program based on quantifications of AAT levels by radial immunodiffusion on venous blood, individuals with values that were below the defined point of AAT deficit (< 100 mg/dl) underwent phenotyping via isoelectric focusing (IEF). In other Group we used genotypic analysis of DNA obtained from dried blood spot (DBS),we included 7 patients, without previous quantifications of AAT levels.
RESULTS: Of the phenotyping group we studied (30 men, 33 women, mean age of 65 years). In 7 patients were found below AAT levels,of which 2 were PiMZ and 1 patient was identified as PiMS, 2 patients were Pi MM and 2 patient was PiM1. PiZZ was not found. In the group based on genotypic analysis (4 men,3 women,mean age 55 years), we found, 1 patient PiMZ, 2 patients with PiMS and 4 patients PiMM. These patients with Pi MZ phenotypes had the lowest AAT levels and greatest reduction in FEV1.
CONCLUSION: A larger study is required to collect sufficient epidemiological data. Patients with the MZ phenotype had a greatest severe COPD. We used IEF for phenotyping, a technique with high specificity however detection program using faster sampling method like DBS will be of widespread benefit in the accurate identifying individuals with deficiency .
CLINICAL IMPLICATIONS: We found PiMZ and PiMS phenotypes, the database indicates that there are carriers 6/71 patients (8.4%).
DISCLOSURE: Xavier Bocca, None.