| 
      χ2: Chi square test between control and other groups. *: Statistical significance at
    p ≤ 0.05
        |  | Control | Asthma | COPD |  
        |  | No | % | No | % | No | % |  
        | Genotype |  |  |  |  |  |  |  
        | CC | 11 | 18.3 | 26 | 52.0 | 15 | 37.5 |  
        | CT | 40 | 66.7 | 22 | 44.0 | 21 | 52.5 |  
        | TT | 9 | 15.0 | 2 | 4.0 | 4 | 10.0 |  
        | χ2 (p) |  |  | 14.976*(0.001) | 4.642 (0.098) |  
        |  |  |  |  |  |  
        | Allele    frequency |  |  |  |  |  |  |  
        | C | 51 | 51.0 | 48 | 52.2 | 36 | 59.0 |  
        | T | 49 | 49.0 | 44 | 47.8 | 25 | 41.0 |  
        | χ2 (p) |  | 0.026 (0.871) | 0.980 (0.322) |  |