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13. Definere begrebet genterapi samt forklare begrundelsen ved brugen af
genterapi
Devlin, s.319-20, cc.7.8
Devlin, s.191, cc.4.6
Gene therapy – introduction of new or altered genes into cells to correct a genetic defect or treat a disease. Individuals who posses a defective gene resulting in a debilitating or fatal condition could theoretically be treated by supplying their cells with a normal gene.
Two basic principles:
Replacing a defective gene with a normal one.
Genes could be engineered either to supply missing proteins or to circumvent the problems caused by the disease.
Several major problems impede the process:
It is very
difficult to introduce the genes to the relevant cells, it is difficult to
target the gene to a particular organ
Inserting the gene
in the cell can also be a problem. The biggest success is achieved using
retroviral vectors
The introduced genes have the tendency to incorporate randomly into the genome, most often by nonhomologous recombination due to a double strand break repair process. The gene can be incorporated into another gene sequence, resulting in the inactivation of the respective gene - mutation; it can also incorporate into the “junk-DNA” that plays a role in the regulation of gene expression - disregulation.
More then 4000 different genetic diseases are known, many of which are debilitating or fatal. Most are currently incurable; however few genetic diseases can readily be treated with gene therapy and the potential is huge.
The first gene therapy treatment was used in 1990.
It must be pointed out that the success rate of gene therapy is higher when the gene is introduced in the cells in vitro and tested, and afterwards reintroduced in our body, fx - blood cells.
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