SERPINA1 and chronic obstructive pulmonary disease: The frequency of Pi*S and Pi*Z alleles among wheezing children is close to the frequency of these alleles among COPD patients: Pi*S 10.3 (95% CI: 4.0–16.6) vs. 15.8 (95% CI: 6.92–24.6) and Pi*Z 44.8 (95% CI: 32.1–57.5) vs. 46.1 (95% CI: 31.1–60.9).