Protease inhibitor phenotypes and serum alpha-1-antitrypsin levels in patients with COPD: a study from Hong Kong

Respirology. 2004 Jun;9(2):265-70. doi: 10.1111/j.1440-1843.2004.00560.x.


Objective: Many studies have suggested that an imbalance of protease activation and inhibition might result in COPD with emphysema. Levels of alpha-1-antitrypsin (alpha1-AT), the key protease inhibitor, are genetically determined by alleles that present in many phenotypes/subtypes, some of which are associated with deficiency of the protein. We prospectively evaluated the prevalence of the protease inhibitor (Pi) alleles and phenotypes together with the serum alpha1-AT levels in Chinese patients with COPD.

Methodology: The study population comprised 356 patients with COPD. The male-to-female ratio was 4 : 1 with a mean age of 72.4 years (range 44-93 years). Isoelectric focusing was used for Pi phenotyping/subtyping. The frequencies of Pi alleles and phenotypes were compared with the frequencies in 1085 healthy unrelated Chinese control subjects. The serum alpha1-AT levels were measured by the Cobas Fara assay.

Results: PiZ was not detected. No significant difference in distribution of PiM phenotypes/subtypes between patients with COPD and healthy controls was observed, except for M1M3 and M2M3. There was also a significant difference in the proportion of variant S and F alleles between the disease group and the control population.

Conclusion: The low prevalence of deficiency Pi phenotypes/subtypes suggests a lack of contribution of alpha1-AT deficiency to the pathogenesis of COPD in Chinese patients. The strategy of launching an alpha1-AT deficiency detection program among COPD patients, based on the recommendation of the World Health Organization, may not be readily applicable in our local setting.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alleles
  • Asian People / genetics
  • China
  • Female
  • Humans
  • Isoelectric Focusing
  • Male
  • Middle Aged
  • Phenotype
  • Prospective Studies
  • Protease Inhibitors / blood*
  • Pulmonary Disease, Chronic Obstructive / blood*
  • alpha 1-Antitrypsin / analysis*


  • Protease Inhibitors
  • SERPINA1 protein, human
  • alpha 1-Antitrypsin