Transcript Slide 1

Your genome:
What does your DNA say about you?
Personal Genetics Education Project (pgEd)
Harvard Medical School
www.pged.org
personal genetics education project
http://www.flickr.com/photos/barl0w/3036412907
• Our genome is our unique code of DNA that carries the information
that affects our traits, including our appearance, behavior, and health.
• Each of us inherited half of our genome from our mother and half
from our father, and this is why we often share traits with our parents.
• As a result, siblings that share parents often share traits.
personal genetics education project
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• DNA is a chemical made up of a chain of bases. There are 4 types of
bases – A, C, G and T.
• In humans, our genome consists of ~3 billion bases.
• Chains of bases are called chromosomes. The number of chromosomes
and the order of bases along each chromosome are very important.
• Each chromosome carries segments of DNA, known as genes, that are
the blueprints to make proteins.
personal genetics education project
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• In general, we each have 23 pairs of chromosomes. One chromosome
from each pair comes from our mother and one from our father.
• Therefore, in general, we inherit two copies of each gene. Our genomes
contain approximately 20,000 genes.
• Genome sequencing determines the order of the 3 billion bases of our
genome and can reveal information about our traits.
Genetic diversity
Our genomes are over 99% identical
Remaining <1% difference => GENETIC VARIATION
personal genetics education project
Genetic diversity
Our genomes are over 99% identical
Remaining <1% difference => GENETIC VARIATION
Terminology: How do we talk about our genetic differences?
MUTATIONS
VARIANTS
personal genetics education project
Genetic diversity
Our genomes are over 99% identical
Remaining <1% difference => GENETIC VARIATION
Terminology: How do we talk about our genetic differences?
MUTATIONS
VARIANTS
personal genetics education project
Pedigrees depict family history
Example: A family where a trait appears in 2 out of 3 children
Dad
Son
(unaffected)
Mom
Twin son
(affected)
Twin daughter
(affected)
personal genetics education project
Pedigrees represent families– the Beerys
Joe
Retta
Zach
Noah
Alexis
http://www.nature.com/news/2011/110615/full/news.2011.368.html
personal genetics education project
Pedigrees depict family history
Example: A family with inherited breast cancer susceptibility (BRCA1 variant)
Steven
Maria
age 60
breast cancer
Vanessa
Emily
Angela
Malcolm
XX
Chris
Ashley
personal genetics education project
Pedigrees depict family history
Example: A family with inherited breast cancer susceptibility (BRCA1 variant)
Steven
Maria
age 60
breast cancer
Vanessa
age 55
breast cancer
Emily
Angela
age 45
ovarian cancer
Malcolm
XX
Chris
Ashley
Justin
age 32
surgery
Chloe
personal genetics education project
A major goal of genetics research is to understand the relationship
between your DNA and your traits
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http://www.flickr.com/photos/wellcomeimages/
5814818738/sizes/l/in/photostream/
Appearance
Behavior
Health
personal genetics education project
Even identical twins are different:
DNA alone does not determine who we are
http://www.flickr.com/photos/wellcomeimages/
5814818738/sizes/l/in/photostream/
http://www.flickr.com/photos/w4nd3rl0st/6789227
039
Appearance
Behavior
Health
http://www.flickr.com/photos/barl0w/3036412907
Environment and
Social Factors
personal genetics education project
Complex relationship between our DNA and the environment
DNA alone does not determine who we are
Examples:
PKU (phenylketonuria):
A genetic disease with an
environmental cure (diet)
http://www.flickr.com/photos/wellcomeimages/
5814818738/sizes/l/in/photostream/
Inherited cancer susceptibility:
Women with same BRCA1 variant
differ in whether they develop
cancer, type of cancer, and age
of onset
Type 2 Diabetes:
Common disease with environmental
and genetic contributions.
http://www.flickr.com/photos/barl0w/3036412907
Environment and
Social Factors
personal genetics education project
DNA: Your personal health risk forecast
1. A weather forecaster makes predictions about if it will rain.
• Your DNA makes predictions about you (i.e. what is your risk for disease?)
It is not a guarantee.
personal genetics education project
DNA: Your personal health risk forecast
1. A weather forecaster makes predictions about if it will rain.
• Your DNA makes predictions about you (i.e. what is your risk for disease?)
It is not a guarantee.
1.
The forecast might be <10% chance of rain, a 30% chance, or a 90% chance. And
weather forecasts often change based on new information.
• In some cases, your DNA might suggest a strong risk of disease. For other diseases,
your risk might be lower. As new risk factors are found, these numbers might change.
personal genetics education project
DNA: Your personal health risk forecast
1. A weather forecaster makes predictions about if it will rain.
• Your DNA makes predictions about you (i.e. what is your risk for disease?)
It is not a guarantee.
1.
The forecast might be <10% chance of rain, a 30% chance, or a 90% chance. And
weather forecasts often change based on new information.
• In some cases, your DNA might suggest a strong risk of disease. For other diseases,
your risk might be lower. As new risk factors are found, these numbers might change.
3. How does the forecast affect whether you’d go out? Or whether you’d bring an umbrella?
• With a 90% chance of rain, you might decide to stay in. With a 50% chance, maybe you
would decide to go out but bring an umbrella. The probability that you will develop
a disease may influence the choices that you make.
personal genetics education project
DNA: Your personal health risk forecast
1. A weather forecaster makes predictions about if it will rain.
• Your DNA makes predictions about you (i.e. what is your risk for disease?)
It is not a guarantee.
1.
The forecast might be <10% chance of rain, a 30% chance, or a 90% chance. And
weather forecasts often change based on new information.
• In some cases, your DNA might suggest a strong risk of disease. For other diseases,
your risk might be lower. As new risk factors are found, these numbers might change.
3. How does the forecast affect whether you’d go out? Or whether you’d bring an umbrella?
• With a 90% chance of rain, you might decide to stay in. With a 50% chance, maybe you
would decide to go out but bring an umbrella. The probability that you will develop
a disease may influence the choices that you make.
4. Sometimes it rains when the forecast expects <10% chance of rain.
• If your risk for disease is >90%, this still means 10 people out of 100 on average will not
develop the disease. If your risk is 1%, 1 person in 100 is expected to get sick.
personal genetics education project
DNA: Your personal health risk forecast
1. A weather forecaster makes predictions about if it will rain.
• Your DNA makes predictions about you (i.e. what is your risk for disease?)
It is not a guarantee.
1.
The forecast might be <10% chance of rain, a 30% chance, or a 90% chance. And
weather forecasts often change based on new information.
• In some cases, your DNA might suggest a strong risk of disease. For other diseases,
your risk might be lower. As new risk factors are found, these numbers might change.
3. How does the forecast affect whether you’d go out? Or whether you’d bring an umbrella?
• With a 90% chance of rain, you might decide to stay in. With a 50% chance, maybe you
would decide to go out but bring an umbrella. The probability that you will develop
a disease may influence the choices that you make.
4. Sometimes it rains when the forecast expects <10% chance of rain.
• If your risk for disease is >90%, this still means 10 people out of 100 on average will not
develop the disease. If your risk is 1%, 1 person in 100 is expected to get sick.
5. Does the forecast predict how hard it will rain?
• Even for a disease like cystic fibrosis, the severity of symptoms vary for individuals with
the same variant in the CFTR gene (due to additional genetic and environmental factors).
personal genetics education project
There are multiple ways to express a 1 in 10 risk
1 in 10 people
10% risk
3 students in your class
(of 30)
3-fold lower risk,
assuming the population risk is 3 in 10
personal genetics education project
For more information, please visit us at www.pged.org
personal genetics education project