Gene Therapy

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  • Gene Therapy
    • Inserting a normal gene/DNA sequence to replace the faulty gene
    • Ways to Correct Faulty Genes
      • Normal gene is inserted into a non specific location within the genome to replace a non-functioning gene.
      • Abnormal gene is swapped for a normal gene by homologous recombination
      • Abnormal gene could be repaired through selective reverse mutation, returning the gene to its normal function
      • Regulation of a particular gene could be altered
    • 2 Ways of Replacing Faulty Genes
      • Gene therapy involving somatic cell therapy targets cells in the affected tissues
        • This method may be therapeutic but the genes are not inherited
      • Germ-line Therapy involves the introduction of corrective genes into germ-line cells (oocyte or sperm)
        • The gene is replaced in the egg and will enable genetic corrections to be inherited
    • How Does It Work?
      • A carrier molecule called a 'vector' must be used to deliver the therapeutic gene to the patient's target cells
      • Most common vector is a VIRUS that has been genetically altered to carry normal human DNA
      • Target cells are infected with the viral vector and the vector unloads the genetic material carrying the therapeutic gene into the target cells
        • Target cells are returned to a 'normal' state.
      • Liposomes can also be used as vectors as they are capable of passing DNA through the target cell's membrane
    • Factors preventing it from becoming an effective treatment for genetic disease
      • Short-lived nature
        • Therapeutic DNA introduced to target cells must remain functional and the cells must be long-lived and stable
          • The rapidly dividing nature of many cells prevents therapeutic gene therapy from achieving long term benefits
      • Immune Response
        • Immune systems are designed to attack any foreign invader introduced into human tissues
          • Reduces the effectiveness of gene therapy
      • Problems with Viral Vectors
        • Potential problems with patients include toxicity, immune and inflammatory responses
          • Gene control
        • Has the potential to recover its ability to cause disease once inside the patient
      • Multigene Disorders
        • Most common diseases are caused by a combination of effects in multiple genes
          • Alzeimers
          • Heart Disease
          • Diabetes
          • Difficult to treat effectively


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