Human Therapeutics


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Human Therapeutics

  1. 1. Human Therapeutics <ul><li>How is our knowledge of DNA technology being used </li></ul><ul><li>today in human therapeutics? </li></ul><ul><li>Congenital abnormalities are genetically based diseases and there therefore inherited </li></ul><ul><li>2 types: </li></ul><ul><ul><li>MONOGENIC : </li></ul></ul><ul><ul><li>POLYGENIC : </li></ul></ul>caused by a single gene defect ( Cystic Fibrosis, Sickle Cell Anaemia, Haemophilia ) caused by defects in several genes ( Heart Disease, Diabetes, Obesity, some cancers )
  2. 2. Detecting genetic disorders <ul><li>Characteristics of a monogenic disease usually begins with </li></ul><ul><li>the presentation of disease symptoms </li></ul><ul><li>Step 1 : Trace disease through family using PEDIGREE ANALYSIS to determine if the faulty gene is dominant , recessive or X-linked (crucial for genetic counselling ) </li></ul><ul><li>Step 2 : Genetic maps are used to identify genetic markers, co- inherited along with the disease. Recombination frequencies give the distance of the marker to the diseased gene. The marker is then located on a more detailed physical map . The gene is then tracked down, characterised and sequenced , leading to accurate diagnostic procedures and potential new treatments </li></ul>
  3. 3. Cystic Fibrosis (CF)
  4. 4. Duchenne Muscular Dystrophy (DMD)
  5. 5. X linked inheritance of Duchenne Muscular Dystrophy Autosomal Recessive Inheritance of Cystic Fibrosis
  6. 6. Mini-project <ul><li>Using either CF or DMD as a case study, write a report about the discovery and treatment of the disease making sure to : </li></ul><ul><ul><li>explain the genetic mutation involved </li></ul></ul><ul><ul><li>describe the methods/tests used to detect genetic disorders such as Cystic Fibrosis and Duchenne Muscular Dystrophy; </li></ul></ul><ul><ul><li>explain the importance of genetic counselling; </li></ul></ul><ul><ul><li>explain how gene therapy could be used to treat genetic disorders; </li></ul></ul><ul><ul><li>include some analysis of results of gene therapy trials; </li></ul></ul><ul><ul><li>discuss the legal, moral and ethical issues for the future </li></ul></ul><ul><li> uk & http://www.who. int /genomics/ elsi /en/ </li></ul>
  7. 7. Gene Therapy <ul><li>When a gene defect such as CF or DMD has been identified and the gene cloned, there is a possibility of using the ‘ good’ copy of the gene to overcome the problem </li></ul><ul><li>This is known as GENE THERAPY : The replacement of a ‘faulty’ gene with a ‘normal’ gene and/or the insertion of an extra gene with the intention that the gene product will play a therapeutic role </li></ul><ul><li>Therefore, the cause of the disease is targeted rather than the symptoms </li></ul>
  8. 8. Gene therapy can be used to … <ul><ul><li>add functioning genes to cells that have lost the gene </li></ul></ul><ul><ul><li>inhibit the spread of a virus e.g. by preventing DNA replication </li></ul></ul><ul><ul><li>kill abnormal human cells by inserting killer genes directly into a patient’s tumour (they will only kill the cells expressing those genes) </li></ul></ul><ul><ul><li>add genes that will specifically inhibit oncogenes or their products </li></ul></ul><ul><ul><li>add genes that make them more susceptible to chemo or radiotherapy </li></ul></ul>
  9. 9. <ul><li>Gene therapy can only be used however, when the following conditions are met:- </li></ul><ul><ul><li>1) The normal gene is available in a cloned form </li></ul></ul><ul><ul><li>2) The affected cells are accessible (either in vivo or ex vivo ) </li></ul></ul><ul><ul><li>3) There are suitable vehicles for delivery of the gene (viral vectors, lyposomes, artificial DNA) </li></ul></ul><ul><ul><li>4) The gene functions normally in its target cells ( i.e. it produces functioning gene product) </li></ul></ul>
  10. 10. <ul><li>Both CF and DMD are potential candidates for gene therapy. But in order for the genes to be dlivered to the correct target cells, suitable VECTORS must be used. To decide the vector, several factors must be decided upon: </li></ul><ul><ul><li>efficiency of delivery to the target cell </li></ul></ul><ul><ul><li>specificity of the delivery to the target cell </li></ul></ul><ul><ul><li>whether the vector will provoke an immune response </li></ul></ul><ul><ul><li>the size of the DNA the vector can carry </li></ul></ul><ul><ul><li>stability and longevity once delivered </li></ul></ul><ul><ul><li>expression of the gene in the target cell </li></ul></ul>
  11. 11. Ethical Issues in Gene Therapy <ul><li>Are we PLAYING GOD? </li></ul><ul><li> uk </li></ul>