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The stop mutation R553X in the CFTR gene results in exon skipping
J Hull1, S Shackleton, A Harris
1Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, England.
Abstract:
Stop or nonsense mutations are known to disrupt gene function in a number of different ways. We have studied the effects of the stop mutation R553X in exon 11 of the CFTR gene by analyzing mRNA extracted from nasal epithelial cells harvested from patients with cystic fibrosis. Four patients who were compound heterozygotes for the R553X mutation were studied. Ten non-CF control subjects were also studied. In all four patients, full-length CFTR mRNA was identified, but only a very small proportion of this was derived from the R553X allele. A smaller transcript, lacking exon 11, was also seen in the R553X patients but not in the controls. Most of this transcript was derived from the R553X allele. These results suggest that the R553X mutation results in skipping of the exon in which it is located.
Insights
The R553X mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene causes exon 11 skipping. This leads to reduced full-length CFTR mRNA in patients with cystic fibrosis.
Area of Science:
- Genetics
- Molecular Biology
- Medical Research
Background:
- Nonsense mutations disrupt gene function through various mechanisms.
- The CFTR gene is crucial for cystic fibrosis pathogenesis.
Purpose of the Study:
- To investigate the functional consequences of the R553X stop mutation in the CFTR gene.
- To analyze mRNA transcripts in cystic fibrosis patients carrying the R553X mutation.
Main Methods:
- Analysis of mRNA from nasal epithelial cells of cystic fibrosis patients and healthy controls.
- Studied four patients with compound heterozygous R553X mutations and ten non-CF controls.
Main Results:
- Full-length CFTR mRNA was detected in R553X patients, but predominantly from the non-mutated allele.
- A shorter transcript lacking exon 11 was observed in R553X patients, mainly from the mutated allele.
- Exon 11 skipping was identified as a consequence of the R553X mutation.
Conclusions:
- The R553X mutation in CFTR induces exon 11 skipping.
- This splicing defect contributes to reduced functional CFTR in cystic fibrosis patients.