Although Cystic Fibrosis is a monogenic disease there is a great clinical diversity among patients, even among those carrying the same mutations in the CFTR gene and the degree of organ involvement and the severity of the disease seem to be linked not only to the amount of functional CFTR and to organ’s sensitivity to CFTR dysfunction but also to the influence of both genetic background of patient and environmental factors [20,21]. Here, CFTR is linked to cystic fibrosis.