However, this should not have biased the results concerning the deleterious effects of CF/CFTR-RD mutations on survival in patients with early-onset DB, in whom the presence of a mutation was found to lead to a mean decrease in survival of 7.1 years on average (log rank test  = 6.3; 1 df; P = 0.012). Here, CFTR is linked to cystic fibrosis.