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Gene therapy involves inserting copies of a normal allele into the chromosomes of an individual who carries the faulty cystic fibrosis allele. It is not always successful, and research is continuing.

It is illegal to insert genes into sex cells, because any changes would be inherited by the individual’s offspring. Instead, gene therapy is used on body cells. It means the individual could pass on their faulty allele to their children, even if they get better themselves.

The basic process

Gene therapy for cystic fibrosis involves these basic steps:

• cutting out the normal allele – special enzymes are used to do this
• making many copies of the allele
• putting copies of the normal allele into the cells of a person who has the disorder

Potential problems

The main difficulty is usually the last step. Some of the problems associated with it include:

• the alleles may not go into every target cell
• the alleles may join with the chromosomes in random places, so they do not work properly
• treated cells may be replaced naturally by the patient’s own untreated cells

Different methods

Different methods are used to get the alleles into the patient’s cells, including:

• using liposomes which are fat droplets in nose sprays
• using cold viruses that are modified to carry the allele – the viruses go into the cells and infect them
• the direct injection of DNA

Issues surrounding the development and use of gene therapy

Research into gene therapy to treat cystic fibrosis can be very expensive. If successful, it only works for a short period as the epithelial cells of the windpipe which accept the gene are constantly worn away. Therefore it is not a long term solution as it has be continually reintroduced.

Here are other factors to consider.

• There may be an immune response by the patient to the introduced gene.
• This therapy offers hope to patients to live a normal life but it is not guaranteed.
• Religious groups believe that humans should not be genetically manipulated.