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OMSI Science Pub - Genetics

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"Genetic Testing: Do You Really Want To Know What's In Your Genes?"

This Science Pub took place at the Bagdad Theater in Portland, Oregon, on Monday, July 6, 2009. It was presented by Dr. Lisa Sardinia, Associate Professor at Pacific University and Associate director of the Pacific Institute for Ethics and Social Policy.

http://www.pacificu.edu/as/biology/faculty/sardinia.cfm

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OMSI Science Pub - Genetics

  1. 2. Lisa Sardinia, J.D., Ph.D. Associate Professor, Pacific University Associate Director, Pacific Institute for Ethics & Social Policy Genetic Testing: Do You Really Want to Know What’s in Your Genes?
  2. 3. What are the types of genetic testing? <ul><li>Diagnostic </li></ul><ul><li>Predictive </li></ul><ul><li>Carrier </li></ul><ul><li>Newborn </li></ul><ul><li>Prenatal </li></ul><ul><li>Pre-implantation </li></ul><ul><li>Forensic </li></ul>
  3. 4. Diagnostic Genetic Testing <ul><li>identify or rule out a specific genetic or chromosomal condition </li></ul><ul><li>often used to confirm a diagnosis based on physical signs and symptoms </li></ul>congenital myotonic dystrophy hemochromatosis
  4. 5. Predictive Genetic Testing <ul><li>detects gene mutations associated with disorders that appear later in life </li></ul><ul><li>frequently provides a probability, not a certainty, that a disorder will occur </li></ul>familial adenomatous polyposis ApoE4 & Alzheimer’s Disease
  5. 6. Carrier Screening <ul><li>identifies people who carry one copy of a gene mutation that, when present in two copies, causes a genetic disorder </li></ul><ul><li>provides info on a couple’s risk of having a child with a genetic disorder </li></ul>
  6. 7. Newborn Screening <ul><li>used just after birth to identify genetic disorders that can be treated early in life </li></ul><ul><li>All states test for phenylketonuria & congenital hypothyroidism </li></ul><ul><li>Oregon tests for 34 disorders </li></ul>
  7. 8. Prenatal Genetic Testing <ul><li>used to detect genetic or chromosomal disorders in a fetus during pregnancy </li></ul><ul><li>hundreds of tests available--few are routine </li></ul>
  8. 9. Preimplantation Genetic Diagnosis <ul><li>detects genetic changes in embryos produced by IVF </li></ul><ul><li>testing done prior to implantation/pregnancy </li></ul>
  9. 10. Forensic DNA Testing <ul><li>uses DNA sequences to identify an individual for legal purposes </li></ul><ul><li>not used to detect gene mutations associated with a disease </li></ul>
  10. 11. How is genetic testing done? <ul><li>We need to make a short digression here…. </li></ul>
  11. 12. What is a gene? <ul><li>basic physical & functional unit of heredity </li></ul><ul><li>made up of DNA </li></ul><ul><li>composed of subunits called bases (A, C, G, T) </li></ul><ul><li>vary in size from a few hundred DNA bases to more than 2 million bases </li></ul><ul><li>The Human Genome Project has estimated that humans have between 20,000 and 25,000 genes </li></ul>
  12. 13. Where are genes? <ul><li>In every cell, wound up to form chromosomes </li></ul>
  13. 14. What does a gene do? <ul><li>contains instructions to build all the proteins that make our bodies function </li></ul><ul><li>passes genetic information to offspring </li></ul>
  14. 15. For example… <ul><li>Red blood cells transport oxygen throughout our bodies using a protein called hemoglobin </li></ul>
  15. 16. <ul><li>If the hemoglobin gene is normal, the instructions will be used to make a normal hemoglobin protein </li></ul><ul><li>But if the instructions are changed, or mutated , changes in the hemoglobin protein could result </li></ul><ul><li>One such mutation causes the disorder sickle cell anemia </li></ul>
  16. 17. Genes can be inherited…
  17. 18. Back to genetic testing <ul><li>the goal is to provide information about a person’s genes and chromosomes, including gene variants that can result in disorders </li></ul>
  18. 19. So, once again, how is genetic testing done? <ul><li>Tissues tested include: </li></ul><ul><ul><li>blood </li></ul></ul><ul><ul><li>skin </li></ul></ul><ul><ul><li>cheek cells </li></ul></ul><ul><ul><li>hair follicles </li></ul></ul><ul><ul><li>embryonic cells </li></ul></ul><ul><ul><li>placental tissue </li></ul></ul><ul><ul><li>amniotic fluid </li></ul></ul>
  19. 20. Methods of Genetic Testing <ul><li>Cytogenetic analysis </li></ul><ul><li>DNA Analysis </li></ul>
  20. 21. Cytogenetic Analysis normal karyotype trisomy 21 Down syndrome
  21. 22. FISH
  22. 23. DNA Analysis
  23. 24. DNA Analysis
  24. 25. Complications….
  25. 26. Carrier frequency of cystic fibrosis Ethnicity Carrier frequency Caucasian (non-Hispanic) 1/25 Ashkenazi Jewish 1/25 Hispanic American 1/46 African American 1/65 CF carrier risk after a negative result for 32 mutations Ethnicity Carrier frequency Caucasian (non-Hispanic) 1/240 Ashkenazi Jewish 1/800 Hispanic American 1/146-1/167 African American 1/207
  26. 27. Tricky stuff-- Predictive genetic testing
  27. 28. Trickier stuff-- Predictive genetic testing…. with probabilities <ul><li>Cancer </li></ul><ul><li>Alzheimer’s disease </li></ul><ul><li>Type II diabetes </li></ul>
  28. 29. Cancer
  29. 30. Two-hit hypothesis
  30. 31. Alzheimer’s disease: Apolipoprotein E
  31. 32. Type II diabetes: Genome-wide association study
  32. 33. I am my genome https://www.23andme.com/ http://www.navigenics.com/ http://www.decodeme.com/ http://www.personalgenomes.org/ http://jimwatsonsequence.cshl.edu/cgi-perl/gbrowse/jwsequence/
  33. 34. Brave new world? http://www.txfertility.com/ivf-program/pgs.html
  34. 35. Want more? <ul><li>Pacific Institute for Ethics & Social Policy </li></ul><ul><li>Fall Programming </li></ul><ul><li>Genetic Testing: Science—Ethics—Public Policy </li></ul><ul><ul><ul><li>Community seminars (September-November) </li></ul></ul></ul><ul><ul><ul><li>Town Hall panel discussion (November 18th) </li></ul></ul></ul><ul><li>http://www.pacificu.edu </li></ul>

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