Cystic fibrosis (CF) is an inherited disorder characterized by multi-organ involvement and displays a wide variation in how the disease affects one individual as compared to another.  Because of this, patients with CF may exhibit a wide range of lung disease from very mild to very severe.  Additionally, a small group of CF patients (2 - 5%) develop severe liver disease.  At a molecular level, the pathogenesis of CF is attributable to over 1000 known mutations within the cystic fibrosis transmembrane conductance regulator (CFTR) gene.  Researchers also believe that other non-CF genes may contribute to the mildness or severity of CF disease.  These modifier genes may directly or indirectly have an effect on how the body responds to the altered conditions that develop as the result of defective CFTR. 

This study has been designed to compare the overall genetic make up of CF patients, in regard to gene modifiers, who are considered to have mild disease versus more severe disease.  Blood samples from volunteers will be studied, along with pulmonary function tests and other medical information, in hopes that a connection can be made between genetic make-up and disease severity of CF lung disease, as well as the development of CF liver disease.

The identification of modifier genes that influence disease severity may ultimately lead to a better understanding of cystic fibrosis, and may be useful in the development of new treatments.  The Cystic Fibrosis Foundation sponsors this trial.