CFTR and chronic obstructive pulmonary disease: Unlike Gervais et al., we did not demonstrate an increased association in the F508del CFTR allele and chronic bronchitis, however this study observed the association in individuals with elevated sweat chloride in an era before comprehensive CFTR genetic analysis, potentially resulting in the inclusion of patients with a mild form of cystic fibrosis due to two unrecognized CFTR mutations; smoking related COPD was also not specified in this report [21].