Distribution of α1-Antitrypsin Alleles in Patients With Bronchiectasis

Abstract

Bronchiectasis has been reported in a few patients with homozygous alpha(1)-antitrypsin (AAT) deficiency, but the distribution of AAT alleles among bronchiectatic patients is not known. Two hundred two patients, 104 men and 98 women, with a mean age (SD) of 63.7 +/- 15.4 years, had bronchiectasis diagnosed by CT scan alone (n = 178), bronchography with or without CT scan (n = 17), or radiography alone (n = 7). AAT phenotypes (classified according to the protease inhibitor [PI] system) were determined by isoelectric focusing in blood samples obtained from all patients. Bronchiectasis was primary in 121 cases and secondary in 81 patients. Allele and phenotype frequencies were compared retrospectively between bronchiectatic patients and healthy blood donors living in the same geographic area. The PI phenotype frequencies among patients were the following: MM, 81.18%; MS, 11.88%; MZ, 3.46%; IZ, 0.49%; IM, 0.49%; SS, 1.48%; SZ, 0.49%; and ZZ, 0.49%. The allelic frequencies among patients were the following: M, 89.1%; S, 7.67%; Z, 2.72%; and I, 0.49%. There was no difference in the distribution of alleles or phenotypes either between patients and control subjects or between patients with secondary and primary bronchiectasis. A significant difference was found between bronchiectatic patients with and without coexisting emphysema (p = 0.028). This difference was caused by an overrepresentation of PI*Z alleles in bronchiectatic patients with coexisting emphysema. Our results do not support a physiopathologic implication of the AAT genes in the development of bronchiectasis. We suggest that bronchiectasis may be a consequence of emphysema in PI*Z patients rather than a primary effect.