Heterozygosity in the Pi-system as a pathogenetic cofactor in chronic obstructive pulmonary disease (COPD)

Area of Science:

• Pulmonary Medicine
• Genetics
• Biochemistry

Background:

• Chronic Obstructive Pulmonary Disease (COPD) is a major health concern.
• Alpha 1-antitrypsin (AAT) deficiency is a known genetic risk factor for COPD.
• The prevalence and impact of specific Pi-phenotypes in COPD patients require further investigation.

Purpose of the Study:

• To determine the prevalence of different alpha 1-antitrypsin (AAT) Pi-phenotypes in a COPD patient population.
• To evaluate the association between specific Pi-phenotypes and COPD severity.
• To assess the utility of AAT and acid alpha 1-glycoprotein (AAG) ratio for screening.

Main Methods:

• Comparison of Pi-phenotype prevalence in COPD patients (n=526) versus control groups.
• Prospective evaluation of Pi-phenotype impact on COPD severity using pulmonary function tests, X-ray, and clinical assessment.
• Analysis of AAT/AAG ratios for screening potential.

Main Results:

• Significantly elevated proportions of ZZ, SZ, and MZ Pi-phenotypes were observed in COPD patients.
• COPD patients with ZZ, SZ, and MZ phenotypes exhibited significantly worse disease severity compared to MM partners.
• An influence of the MS phenotype could not be rejected.
• The AAT/AAG ratio effectively detected ZZ, SZ, and MZ phenotypes, and approximately 60% of MS phenotypes.

Conclusions:

• Specific AAT Pi-phenotypes (ZZ, SZ, MZ) are more prevalent in COPD patients and associated with increased disease severity.
• Routine phenotyping for AAT deficiency in all COPD patients is recommended.
• AAT/AAG ratio serves as a viable screening method for identifying individuals with AAT deficiency relevant to COPD.