Frequency of alpha-1 antitrypsin deficiency and unexpected results in COPD patients in Turkey; rare variants are common.

Abstract

Alpha-1 antitrypsin (α1-AT) is a protease inhibitor that is largely released from liver cells. It inhibits neutrophil elastase and its deficiency increases the risk of developing chronic obstructive pulmonary disease (COPD). The frequency of α1-AT deficiency has been reported with different prevalence rates in different parts of the world. The most common α1-AT variant causing α1-AT deficiency is the Pi*Z allele. In this study, we aimed to determine the frequency of the α1-AT genotypic variant in COPD patients in our country. In this study, 196 consecutive COPD patients admitted to our clinic were included. In addition to recording the demographic data of the volunteers, a dry drop of blood sample was taken from the fingertip for the SERPINA1 genotype study. One hundred and fifty-eight (80.6%) of the patients were male and the mean age was 56.92 ± 9.84 years. A variant in the SERPINA1 gene was detected in a total of 14 (7.1%) COPD patients. Pi*ZZ homozygous variant was detected in only 1 (0.51%) patient, while Pi*MZ was detected in 3 (1.53%) patients. The Pi*S variant was never detected. Various rare heterozygous variants were detected in 9 (4.6%) patients and a single point mutation was found in one (0.51%) patient. Serum α1-AT levels were significantly lower in patients with variants compared to the Pi*MM group (p < 0.001). In this study, which investigated the genotypic α1-AT variant frequency in COPD patients for the first time in our country, we found that the percentage of homozygous Pi*ZZ patients was 0.51%, but when heterozygous α1-AT gene variant and single point mutation were included, the frequency was 7.1%. At the same time, while the Pi*S variant was never detected, rare variants were found more frequently than expected.