The use of in-depth molecular genetic tests, that detect CFTR mutations of uncertain significance, along with the different approaches in the newborn screening procedures undertaken by different CF centers lead several cases of CF uncertain diagnoses. It is a condition known with the acronym CFSPID (Cystic Fibrosis Screening Positive Inconclusive Diagnosis). This study, thanks to a collaboration between 6 Italian CF centers, is the extension of the FFC#30/2018 project, in which the researchers retrospectively collected data from 2011-2018 time frame: 336 inconclusive diagnoses and 257 diagnoses of CF. Despite some of those CFSPID have in the meantime gained certainty in the diagnosis, thanks to a careful reassessment, most cases remain uncertain. In this study the cases reported in 2018-2021 will be prospectively taken into consideration, for the application of a homogeneous diagnostic and clinical protocol. The goal is to achieve greater uniformity of procedures and management and assess their impact. Furthermore, through a questionnaire sent to all CFSPID, psychological problems that the diagnostic uncertainty entailed will be investigated, to improve approach and communication with family members.