CFTR and cystic fibrosis: In this study, we demonstrated that the contribution of CF patient registries is particularly important in small or isolated populations, such as in Cyprus, where unique genotypic (e.g. documented founder effect in p.Leu346Pro (L346P), presence of complex allele p.Cys1400X with c.489 + 3A > G in cis, relatively common intra-CFTR rearrangement CFTR-dup2, including to a large degree a distinct mutation spectrum from neighbouring populations in the Eastern Mediterranean basin) and particular phenotypic profiles can be found.