Since the degree of clinical benefit changes within a small range of functional CFTR protein, it remains to be seen whether the strong clinical benefit of the treatment with ELX/TEZ/IVA seen in our study and the clinical trials (Heijerman et al., 2019; Middleton et al., 2019) will persist or attenuate over the years in an ageing CF population. The gene discussed is CFTR; the disease is cystic fibrosis.