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Cystic fibrosis is a genetic disorder caused by a mutant allele that produces a defective form of the channel protein, called CFTR. This protein normally transports chloride ions out of the cells. The defective CFTR protein causes chloride ions to build up in the cells. This causes those cells to retain water. In the lungs and intestines this is a particular problem. Water fails to pass into the mucus that lines the airways and gut, causing the mucus to become thick and sticky. In the lungs, this leads to breathing difficulties and the risk of infection; in the gut, the mucus blocks the ducts that carry digestive enzymes. .   Exam Advice

Gene therapy may be able to provide treatments for cystic fibrosis. Healthy genes can be cloned and then transferred to target cells in the body to take over the function of defective genes that cause the disorder.

Two forms of gene therapy are being developed to treat cystic fibrosis.

  • In the first, healthy CFTR genes are inserted into liposomes, which fuse with the cell membranes and take the genes into the cells.
  • In the other, harmless viruses are used to insert the CFTR genes into the cells.

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