COL1A1 expression was positively associated with the amount of collagen in the airway in asthmatics and non-asthmatics (Collagen/Pi, R2 = 0.2221 and 0.2182 for asthma and non-asthma respectively, p < 0.01) and the thickness of the basement membrane in both groups combined (R2 = 0.1313, p = 0.01). This evidence concerns the gene COL1A1 and asthma.