The prevalence of alpha-antitrypsin heterozygotes (Pi MZ) in patients with obstructive pulmonary disease
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Abstract:
An increased incidence of intermediate deficiency of serum alpha1-antitrypsin resulting from Pi phenotype MZ has been reported in patients with chronic obstructive pulmonary disease (COPD) by some laboratories but not confirmed by others. Prevalence of Pi MZ was determined in patients with COPD among 502 subjects referred to a pulmonary function testing laboratory in a region with low concentrations of air pollutants. Control prevalences were obtained from 930 randomly selected subjects in the same community as well as from patients without COPD referred to the laboratory. Depending on criteria used to define COPD, 155 to 306 subjects had COPD. Pi MZ prevalence in subjects with COPD varied from 1.5 to 4 times the prevalence in the community control group and in the patients without COPD. This difference approached significance or was significant. Because Pi MZ was present in only 3.5 to 4.5 per cent of patients with COPD, Pi MZ is not a major factor in the etiology of COPD in this community. The higher incidence of Pi MZ inpatients with COPD reported by other investigators may be explained by small sample size, bias in selection of study or control population groups, or the development of COPD from interaction between Pi MZ and air pollutants or other factors not present in this community.
Insights
The PiZ phenotype, linked to alpha-1 antitrypsin deficiency, is not a major cause of chronic obstructive pulmonary disease (COPD) in this low-pollution community, despite some studies suggesting a link.
Area of Science:
- Pulmonary Medicine
- Genetics
- Epidemiology
Background:
- Conflicting reports exist regarding the association between the PiZ phenotype (intermediate alpha-1 antitrypsin deficiency) and chronic obstructive pulmonary disease (COPD).
- Previous studies have suggested a potential link, but findings have not been consistently confirmed across different populations.
Purpose of the Study:
- To investigate the prevalence of the PiZ phenotype in patients diagnosed with COPD.
- To determine if the PiZ phenotype is a significant risk factor for COPD development in a community with low air pollution.
Main Methods:
- A case-control study was conducted involving 502 subjects referred for pulmonary function testing.
- The prevalence of the PiZ phenotype was compared between COPD patients (155-306 subjects) and control groups (930 community subjects and COPD-free patients).
- Subjects were from a region characterized by low ambient air pollutant concentrations.
Main Results:
- The prevalence of the PiZ phenotype in COPD patients was 1.5 to 4 times higher than in community and non-COPD patient controls.
- This difference approached statistical significance or was significant.
- However, the PiZ phenotype was present in only 3.5% to 4.5% of COPD patients, indicating a low overall contribution.
Conclusions:
- The PiZ phenotype is not a major etiological factor for COPD in this specific low-pollution community.
- Discrepancies with previous research may be attributed to smaller sample sizes, selection bias in study/control groups, or gene-environment interactions (e.g., air pollution) not present in this population.