Human CFTR gene sequences in regions flanking exon 10: a simple repeat sequence polymorphism in intron 9.

A 2,908-bp segment of genomic DNA containing exon 10 and flanking intron regions of the human cystic fibrosis transmembrane conductance regulator gene was sequenced. A 30-bp sequence discrepancy and three missing nucleotides were detected when compared to a previously published 831-bp sequence. In the 30-bp region of sequence discrepancy, only a primer based on the new sequence information presented in this study gave products from polymerase chain reaction amplification of cellular DNA and a plasmid DNA encompassing the exon 10 region of CFTR. A 4-bp (TAAA) simple repeat sequence was also identified in intron 9 region. This repeat is dimorphic with nine (TAAA)9 or eleven (TAAA)11 copies on different chromosomes. Eleven repeats were exclusively associated with chromosomes carrying the delta508 mutation. Both 9 and 11 repeats were detected in non-delta508 chromosomes.