Alpha1-antitrypsin (AAT) deficiency is an under-diagnosed condition in patients with chronic obstructive pulmonary disease (COPD). The objective of the present screening was to estimate the AAT gene frequency and prevalence and to identify AAT deficiency cases in a large cohort of Lithuanian patients with COPD.

A nationwide program of AAT deficiency was conducted in 1167 COPD patients, defined according to the GOLD criteria. Patients were collected from outpatient clinics in five different Lithuanian regions (Kaunas, Vilnius, Siauliai, Klaipeda and Alytus). AAT serum concentrations were measured by nephelometry; PI-phenotypes characterized by isoelectric-focusing.

Mean age and FEV₁ were 62.0 (10.3) and 54.7% (10.9), respectively. Ninety-one AAT deficiency genotypes (40 MZ, 39 MS, 1 SS, 3 SZ and 8 ZZ) were identified. Calculated PIS and PIZ frequencies, expressed in per 1000, were 18.8 (95% CI: 13.9–25) and 25.3 (95% CI: 19.4–32.7), respectively. The calculated AAT gene prevalence (Hardy–Weinberg principle) was: 1/1.09 for MM, 1/28 for MS, 1/2814 for SS, 1/20 for MZ, 1/1049 for SZ and 1/1565 for ZZ. Calculated Odds ratio (OR) for PIZ in COPD vs. Lithuanian healthy people was of 1.87 (P=0.004).

The OR for each genotypic class demonstrated a significant increase of MZ, SZ and ZZ genotypes in COPD patients. The results of the present study, with a significant number of ZZ individuals detected, support the general concept of targeted screening for AAT deficiency in countries like Lithuania, with a large population of COPD patients and low awareness among care-givers about this genetic condition.