Alpha-1-antitrypsin deficiency screening program at the Pneumonology Department of Hospital Tránsito Cáceres de Allende

ABSTRACT

Alpha-1-antitrypsin deficiency (AATD) is a rare genetic disease associated with an increased risk of suffering from pulmonary emphysema and chronic hepatopathy in children and adults alike. It is often underdiagnosed, with long periods elapsing between the onset of symptoms and a definite diagnosis. Alpha-1-antitrypsin (AAT) is the most abundant protease inhibitor in the human body. Scientific literature considers severe deficiency to be associated with the following phenotypes SZ, ZZ and Null. Screening programs are required for early detection, this is why an easy and specific method has been described and validated. Through this method, AAT values are quantified using nephelometry in blood drop samples on blotting paper, then genotyping of the Z and S variants is quickly performed. Objectives: To determine the number of individuals with AATD within a population of patients with chronic respiratory diseases. To identify and define those with AAT deficiency. Materials and Method: Observational, descriptive and cross-sectional study of AAT deficiency screening, between January 2nd, 2014 and March 30th, 2015. Out of 80 individuals who fulfilled the inclusion criteria and who spontaneously attended or were referred to the Pneumonology Department of Hospital Tránsito Cáceres de Allende, Córdoba, Argentina, 62 patients who agreed to the study were analyzed. A test to determine the concentration of alpha-1-antitrypsin was performed to the patients who met all the inclusion criteria using blood drops on blotting paper. Only patients with alpha-1-antitrypsin levels < 1.8 mg/dL were requested a spirometry, a high-resolution computed tomography of the chest and quick genotyping tests. Results: A total of 62 patients was evaluated in this study, 28 (45.2%) were females and 34 (54.8%) were males, 37 (59.7%) had alpha-1-antitrypsin levels ≥ 1.8 mg/dL and 25 (40.3%) < 1.8 mg/dL. Genotype elicitation using the dried-droplet method in 25 (40.3%; 2562) patients with values < 1.8 mg/dL showed that 22 (88%; 2225) were Non-S Non-Z, 2 (8%; 225) were heterozygote for Z and 1 (4%; 125) was heterozygote for S. According to ATS/ERS criteria, the predominant spirometric pattern was obstructive (88%). The HRCT pattern corresponded to emphysema in 22 patients (88%) 7 (31.8%) centrilobular, 8 (36.4%) paraseptal, 7 (31.8%) panlobular. There were 2 patients (8%) with bronchiectasis and 1 (4%) was normal. Conclusion: In a population selected by symptoms and/or history, patients with AATD can be identified using the dried-droplet method. Severe AATD is uncommon in Argentina, probably because it is underdiagnosed, and the amount of heterozygote PIS and PIZ carriers is higher. Early AATD diagnosis is uncommon. It is difficult to draw conclusions about the alpha-1-antitrypsin group below 1.8 mg/dL without severe deficiencies in connection with the variables analyzed in the sample due to the lack of studies and bibliography on this subject. We consider that patients with non-S non-Z genotypes and the ones with discrepancies must be quantitatively confirmed and their phenotype defined in serum samples using isoelectric focusing and, occasionally, they must have a molecular gene analysis to look for uncommon, new or null allelic variants.