Solid Phase Fluorescent Sequencing of the CFTR Gene

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR ) gene (1 –5 ). The CFTR gene spans about 250 kb at the genomic level (6 ). After transcription, a transcript of about 6.1 kb is obtained containing up to 27 exons (2 ,7 ). Several alternatively spliced transcripts have been found (8 –13 ), the most important one of which lacks exon 9 sequences (8 ). The CFTR protein is a glycosylated transmembrane protein (14 ) that functions as a chloride channel (15 ). CFTR is expressed in epithelial cells of exocrine tissues, such as the lungs, pancreas, sweat glands, and vas deferens (1 ). Apart from CF, CFTR is also involved in other diseases such as congenital bilateral absence of the vas deferens (CBAVD) (16 ,17 ), allergic bronchopulmonary aspergillosis (18 ), and bronchiectasis (19 ). More than 850 disease mutations have been described in the CFTR gene (5 ). Apart from these, more than 120 polymorphisms were also found (5 ). The majority of these are point mutations, being missense, nonsense, or splice site mutations, as well as small frameshift mutations (insertions and deletions). Large deletions and insertions are rare.