Figure 3

Aberrant splicing due to c.3700 A>G mutation in cystic fibrosis transmembrane conductance regulator ( CFTR ) predicts a deletion of six amino acids (p.Ile1234_Arg1239del). (a) Strategy for reverse transcriptase–polymerase chain reaction amplification of a region containing exon 19. (b) The amplified product visualized on an agarose gel. The expected size of 499 bp is seen in an unaffected control, whereas a slightly smaller band is seen in the patient. (c) Direct sequence analysis of the fragment in the patient revealed a deletion of the last 18 bp of exon 19. (d) A schematic overview of the genomic DNA with activation of a cryptic donor splice site in exon 19. The c.3700 A>G mutation in exon 19 activates a cryptic donor splice site 18 bp upstream of the original donor splice site. This results in a truncated exon 19 with a predicted deletion of six amino acids (r.3700_3717del; p.Ile1234_Arg1239del) in CFTR. mRNA, messenger RNA.