Predictive value of alpha-1 antitrypsin level for Z mutation detection in chronic obstructive pulmonary disease

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Alpha1-antitrypsin (AAT) deficiency is an under-diagnosed condition in patients with chronic obstructive pulmonary disease (COPD). The aim of our study was to evaluate predictive value of quantitative methods of alpha-1 antitrypsin for Z mutation detection in patients with chronic obstructive pulmonary disease. Ninety-one AAT deficiency genotypes (40  MZ, 39  MS, 1  SS, 3  SZ and 8  ZZ) were analysed. Calculated sensitivity of quantitative alpha-1 antitrypsin measurement by nephe­lometry for heterozygous PI*Z allele was 45% and for homozygous ZZ genotype  –  88%. Specificity of quantitative alpha-1 antitrypsin analysis for heterozygous deficiency was 98% and for homozygous deficiency – 100%. Thus sensitivity of quantitative al­pha-1 antitrypsin analysis is higher than specificity for both – heterozygous and homozygous deficiency.