The mutational spectrum of CFTR in the first group differs from that observed in classic cystic fibrosis, with milder missense or splice variants present on at least one chromosome.
There are two main populations of CAVD; the larger group is associated with cystic fibrosis and occurs because of a mutation in the CFTR gene, while the smaller group (estimated between 10 and 40%) is associated with unilateral renal agenesis (URA).