To overcome these limitations in the future, reporting CFTR-variants in CF-registries should be done in a meticulously way; avoiding typographical errors, entering c.DNA name, protein name and legacy name, if available, and confirming that both mutations are located in trans. This study shows that regular reviews by a geneticist in the CF-field would contribute to better reporting of RM in CF-registries and should therefore be encouraged. This evidence concerns the gene CFTR and cystic fibrosis.