European screening for alpha₁ -antitrypsin deficiency in subjects with lung disease

Background and aims: Alpha₁ -antitrypsin deficiency (AATD) predisposes individuals to early-onset emphysema. Despite its prevalence, especially among patients with chronic obstructive pulmonary disease, AATD is still underdiagnosed. The aim of this study is to identify individuals with lung disease and severe AATD in central-eastern Europe.

Methods: Subjects with respiratory symptoms that could be indicative of AATD provided blood samples as dried blood spot. The alpha₁ -antitrypsin (AAT) concentration was determined by nephelometry and, if lower than 1.70 mg/dL in dried blood spot (equivalent to 1.04 g/L in serum), polymerase chain reaction was used to detect the PiS and PiZ alleles. Isoelectric focusing was used for confirmation of doubtful genotype results.

Results: From 13 countries, 11 648 subjects were included. Genotyping of 1404 samples with AAT levels <1.70 mg/dL revealed 71 (5.06%) PiS, 151 (10.8%) PiZ, 1 (0.071%) PiSS, 8 (0.57%) PiSZ and 32 (2.28%) PiZZ. Phenotyping of 1363 samples negative for the S and Z alleles or with PiS and PiZ genotype showed two (0.147%) PiZ(rare) and two (0.147%) Pi(null)(null). The countries with the highest rate of severe AATD were Croatia, Russia and Slovakia. By regions, the Baltic countries area showed the highest rate of both PiZ and severe AATD (2.45% and 1.20%, respectively) while the lowest rates were observed in the Balkan Peninsula (0.48% and 0.31%, respectively).

Conclusion: This study confirms the need for targeted testing of symptomatic patients and provides AATD genotype data from countries for which only some estimates of prevalence were available until now.