Sweat testing and CFTR gene analysis are very important for the diagnosis of CF. As for the results of the intermediate sweat test without CF-causing variants in a CF diagnosis, CF Foundation guideline proposed the following insight: the absence of the detection of two CF-causing variants does not exclude a diagnosis of CF; there are individuals with a CF diagnosis in whom two CFTR variants have not been detected [2]. This evidence concerns the gene CFTR and cystic fibrosis.