The impact of P. aeruginosa on CFTR thus adds to other factors that may modulate the response to treatments in CF patients, including drug pharmacokinetics, the presence of complex CFTR alleles and modifier genes (Strug et al., 2016), the level of residual CFTR function, the influence of environmental factors and the lung disease severity at the time of treatment initiation. The gene discussed is CFTR; the disease is cystic fibrosis.