In the 1990s, gene therapy was seen as a probable cure for many genetic diseases. List three or four reasons that it has so far been of limited success
What will be an ideal response?
Gene therapy is technically challenging, particularly in the mechanisms of gene delivery and activation in the correct target tissue. The gene must be targeted to the correct tissue to ensure proper wild-type expression. If the gene is targeted to the wrong tissue, it would be inefficient, but could also result in severe health problems by introducing a gene into a tissue which normally does not express that gene product. Similarly, if a gene is intended to be targeted to one particular tissue and is, instead, introduced into the germ line, it may be passed on to offspring with unintended consequences. Instead of expressing the gene only in the targeted tissue, it would now affect all cells in the patient's offspring, which may prove to be fatal or have severe side effects.
Within the individual, gene therapy may inadvertently result in the activation or deactivation of other genes based on where the DNA incorporates into the genome. The viral vector itself can also elicit a severe immune reaction in some individuals, which was the case in early gene therapy trials. In addition, if a construct has been incorporated, it is difficult to control levels of gene expression and the amount of expression may be higher or lower than anticipated.
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Avery, MacLeod, and McCarty's experiments revealed that the transforming principle had all of the following properties except
A. its activity was destroyed by treatment with proteases. B. its activity was unaffected by RNA-digesting enzymes. C. its activity was unaffected by lipid extraction. D. its activity was destroyed by treatment with DNA endonucleases.
Which of the following is not a common mechanism by which antifungal agents work?
A) by binding with cell membrane sterols B) by blocking nucleic acid synthesis C) by dissolving hyphae D) by interfering with sterol synthesis
DNA that is separate and apart from the chromosome in a prokaryote is the:
a. Ribosome b. Endospore c. Nucleus d. Nucleoid e. Plasmid
How can you explain that an adult who had chicken pox, is now at risk of the shingles infection if you know that both diseases are caused by the same virus?
a. This is the same thing as the latent period of an active infection. b. This is akin to the attachment phase of replication. c. This is something that occurs during the lytic cycle. d. The virus has been lying dormant inside the cells for some time and can begin reproducing again later. e. This could never occur.