CFTR and cystic fibrosis: Germline PGt testing can be used in two different frameworks: i) the evaluation of potential benefits of a treatment in presence of a specific genotype, as exemplified by the use of lexacaftor/ ivacaftor/ tezacaftor, prescribed for cystic fibrosis (CF) therapy only in patients with at least one copy of the F508del mutation (NM_000492.4:c.1521_1523del) in the CFTR gene [7]); ii) the investigation of functional genetic variants influencing the pharmacokinetics (PK) and/or the pharmacodynamics (PD) of a drug, thereby affecting the drug’s efficacy, appropriate dosage, and adverse effects.