Sensitivity of alpha-1 antitrypsin level for inherited deficiency detection in COPD patients.

BACKGROUND AND OBJECTIVE Alpha-1 antitrypsin deficiency is an underdiagnosed condition in patients with chronic obstructive pulmonary disease. Diagnosis of this genetic condition is confirmed by genetic verification of pathology, but for screening purposes quantitative methods can be useful. The aim of our study was to evaluate sensitivity and specificity of quantitative methods for alpha-1 antitrypsin deficiency detection. METHODS Serum alpha-1 antitrypsin concentrations from patients (n = 1167) with chronic obstructive pulmonary disease, defined according to the GOLD criteria, were analysed by nephelometry, alpha-1 antitrypsin genotype was determined by means of isoelectric-focusing. RESULTS Eight severe alpha-1 antitrypsin deficiency genotypes in homozygous type (ZZ) and 40 in heterozygous genotype (-Z) were identified. Calculated sensitivity of quantitative alpha-1 antitrypsin measurement by nephelometry for heterozygous PI*Z allele is 45% and for homozygous ZZ genotype is 88%. Specificity of quantitative alpha-1 antitrypsin deficiency determining analysis is 99%. CONCLUSIONS A case detection program of alpha-1 antitrypsin deficiency in patients with chronic obstructive pulmonary disease using quantitative methods is specific, but due to limited sensitivity should be used only in screening programs.