CFTR and cystic fibrosis: Munthe-Kaas et al. found a lack of associations between CFTR mutations (IVS8(TG)mTn haplotypes) and lung function, BHR and increased nitrogen oxide (FeNO); the percentage of CF heterozygosity was higher in subjects without reduced lung function, BHR or increased FeNO levels than in those with the clinical traits.