Gene therapy 1
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  • 1. Gene Therapy Introduction Pages 1-11
  • 2. Gene Therapy
    • Purpose:
      • Introduce a functional gene into a person who lacks this gene
      • Gene therapy is potentially useful for treating recessive diseases
      • Parents are heterozygotes
      • Patients lack a particular enzyme
      • Gene therapy is used to replace the missing enzyme
  • 3. Gene therapy
    • The first disease that gene therapy was used for was Severe Combined Immune Deficiency (SCID)
    • In this disease, there is a lack of the enzyme adenosine deaminase (ADA)
    • Gene therapy is used to give a patient a functional ADA gene
    • Introduce the gene into bone marrow cells and the patient can then produce WBCs throughout their life and produce the enzyme
  • 4.  
  • 5. What diseases should gene therapy be used for?
    • Diseases must result from the defect in a single gene
    • Gene must have been identified and purified
    • Cells affected by the gene defect must be accessible for gene therapy
      • Problems in treating neurological disease
      • Must get past the blood brain barrier
    • Diseases chosen usually have few effective treatments
  • 6. What cells should be targeted to be altered?
    • Gene therapy is for altering somatic or body cells and not germ cells
    • This treatment will be used to correct a defect in an individual but the correction is NOT passed on to subsequent generations
    • Gene therapy is used to treat diseases and not alter characteristics of the next generation
  • 7. Transcription and Translation
    • DNA codes for the gene that you want to insert
      • Insert the gene for ADA to treat SCID
    • If gene therapy is successful, then the ADA enzyme will be made
  • 8.  
  • 9.
    • SCID - ADA
    • Lung cancer - p53 tumor suppressor gene
    • Cystic fibrosis - Cystis fibrosistransmembrane conductance regulator (CFTR)
    • Leukemia - Interleukin 2 (IL-2)
    • Look at table 2, pages 5-7
    Different diseases can be treated by introducing different genes
  • 10. How do you make the recombinant DNA?
    • Vector
      • Plasmid
      • Place to incorporate the foreign DNA
        • The DNA that codes for the missing enzyme
      • A marker gene - antibiotic resistance gene
        • Determine if the vector entered the cell
    • Foreign DNA
  • 11. Steps in making recombinant DNA
    • Need DNA from 2 different sources
      • In this class, we will transfer DNA from one plasmid and put it into another plasmid
    • Cut DNA with restriction enzymes
      • Create staggered or blunt end cuts
    • Match the DNA from the 2 different sources and let them combine
    • DNA ligase seals the 2 pieces together
  • 12.  
  • 13. DNA structure
  • 14.  
  • 15. When performing cloning, how do you find the gene you are interested in?
    • Get a gene library
      • Collection of different genes
    • Use a PROBE to find your gene in this gene library
    • A probe is complementary to your gene of interest
  • 16. How is the PROBE used?
    • Gene sequence = AGCTGGAC
    • Probe = TCGACCTG
    • Heat is used to separate the two strands
    • Probe is added to the gene sequence
    • Probe is labeled at one end with a radioisotope so it can be detected if it binds to the gene
  • 17.  
  • 18. How is the PROBE used?
    • Locate a functional ADA probe to perform gene therapy for SCID
    • Use a gene library from someone who DOES NOT have SCID
    • Use a probe specific for the ADA sequence
    • Isolate the DNA to be used in gene therapy
    • Probes are also used in Southern Blots, Northern Blots and Western Blots