omsi science pub - genetics
DESCRIPTION
"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.cfmTRANSCRIPT
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?
What are the types of genetic testing?
• Diagnostic• Predictive• Carrier• Newborn• Prenatal• Pre-implantation• Forensic
Diagnostic Genetic Testing
• identify or rule out a specific genetic or chromosomal condition
• often used to confirm a diagnosis based on physical signs and symptoms
congenital myotonic dystrophy
hemochromatosis
Predictive Genetic Testing
• detects gene mutations associated with disorders that appear later in life
• frequently provides a probability, not a certainty, that a disorder will occur
familial adenomatous polyposis
ApoE4 & Alzheimer’s Disease
Carrier Screening
• identifies people who carry one copy of a gene mutation that, when present in two copies, causes a genetic disorder
• provides info on a couple’s risk of having a child with a genetic disorder
Newborn Screening
• used just after birth to identify genetic disorders that can be treated early in life
• All states test for phenylketonuria & congenital hypothyroidism
• Oregon tests for 34 disorders
Prenatal Genetic Testing
• used to detect genetic or chromosomal disorders in a fetus during pregnancy
• hundreds of tests available--few are routine
Preimplantation Genetic Diagnosis
• detects genetic changes in embryos produced by IVF
• testing done prior to implantation/pregnancy
Forensic DNA Testing
• uses DNA sequences to identify an individual for legal purposes
• not used to detect gene mutations associated with a disease
How is genetic testing done?
We need to make a short digression here….
What is a gene?
• basic physical & functional unit of heredity
• made up of DNA• composed of subunits
called bases (A, C, G, T)• vary in size from a few
hundred DNA bases to more than 2 million bases
• The Human Genome Project has estimated that humans have between 20,000 and 25,000 genes
Where are genes?
• In every cell, wound up to form chromosomes
What does a gene do?
• contains instructions to build all the proteins that make our bodies function
• passes genetic information to offspring
For example…
• Red blood cells transport oxygen throughout our bodies using a protein called hemoglobin
• If the hemoglobin gene is normal, the instructions will be used to make a normal hemoglobin protein
• But if the instructions are changed, or mutated, changes in the hemoglobin protein could result
• One such mutation causes the disorder sickle cell anemia
Genes can be inherited…
Back to genetic testing
• the goal is to provide information about a person’s genes and chromosomes, including gene variants that can result in disorders
So, once again, how is genetic testing done?
• Tissues tested include:– blood– skin– cheek cells– hair follicles– embryonic cells– placental tissue– amniotic fluid
Methods of Genetic Testing
• Cytogenetic analysis
• DNA Analysis
Cytogenetic Analysis
normal karyotype trisomy 21Down syndrome
FISH
DNA Analysis
DNA Analysis
Complications….
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
Tricky stuff--Predictive genetic testing
Trickier stuff--Predictive genetic testing….
with probabilities
• Cancer• Alzheimer’s disease• Type II diabetes
Cancer
Two-hit hypothesis
Alzheimer’s disease:Apolipoprotein E
Type II diabetes:Genome-wide association study
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/
Brave new world?http://www.txfertility.com/ivf-program/pgs.html
Want more?
Pacific Institute for Ethics & Social Policy
Fall Programming
Genetic Testing: Science—Ethics—Public Policy
•Community seminars (September-November)
•Town Hall panel discussion (November 18th)
http://www.pacificu.eduhttp://www.pacificu.edu