Your genome: What does your DNA say about you? Personal Genetics Education Project (pgEd) Harvard Medical School personal genetics education project

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

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

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.

personal genetics education project Genetic diversity Our genomes are over 99% identical Remaining GENETIC VARIATION

personal genetics education project Genetic diversity Our genomes are over 99% identical Remaining GENETIC VARIATION VARIANTS MUTATIONS Terminology: How do we talk about our genetic differences?

personal genetics education project Genetic diversity Our genomes are over 99% identical Remaining GENETIC VARIATION VARIANTS MUTATIONS Terminology: How do we talk about our genetic differences?

Pedigrees depict family history personal genetics education project DadMom Son (unaffected) Example: A family where a trait appears in 2 out of 3 children Twin son (affected) Twin daughter (affected)

Pedigrees represent families– the Beerys personal genetics education project JoeRetta ZachNoah Alexis

personal genetics education project age 60 breast cancer MalcolmVanessa AngelaAshley Maria Emily Steven Pedigrees depict family history Example: A family with inherited breast cancer susceptibility (BRCA1 variant) XX Chris

personal genetics education project Example: A family with inherited breast cancer susceptibility (BRCA1 variant) Pedigrees depict family history age 60 breast cancer Malcolm Vanessa AngelaAshley Maria Justin age 45 ovarian cancer age 55 breast cancer Chloe age 32 surgery Emily Steven XX Chris

A major goal of genetics research is to understand the relationship between your DNA and your traits ? personal genetics education project Appearance Behavior Health /sizes/l/in/photostream/

Even identical twins are different: DNA alone does not determine who we are personal genetics education project Appearance Behavior Health /sizes/l/in/photostream/ Environment and Social Factors

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) 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. personal genetics education project Environment and Social Factors /sizes/l/in/photostream/

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. DNA: Your personal health risk forecast personal genetics education project

1. A weather forecaster makes predictions about if it will rain. 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. Your DNA makes predictions about you (i.e. what is your risk for disease?) It is not a guarantee. 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. DNA: Your personal health risk forecast personal genetics education project

1. A weather forecaster makes predictions about if it will rain. 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. 3.How does the forecast affect whether you’d go out? Or whether you’d bring an umbrella? Your DNA makes predictions about you (i.e. what is your risk for disease?) It is not a guarantee. 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. 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. DNA: Your personal health risk forecast personal genetics education project

1. A weather forecaster makes predictions about if it will rain. 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. 3.How does the forecast affect whether you’d go out? Or whether you’d bring an umbrella? 4.Sometimes it rains when the forecast expects <10% chance of rain. Your DNA makes predictions about you (i.e. what is your risk for disease?) It is not a guarantee. 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. 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. 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. DNA: Your personal health risk forecast personal genetics education project

1. A weather forecaster makes predictions about if it will rain. 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. 3.How does the forecast affect whether you’d go out? Or whether you’d bring an umbrella? 4.Sometimes it rains when the forecast expects <10% chance of rain. 5.Does the forecast predict how hard it will rain? Your DNA makes predictions about you (i.e. what is your risk for disease?) It is not a guarantee. 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. 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. 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. 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). DNA: Your personal health risk forecast personal genetics education project

There are multiple ways to express a 1 in 10 risk 1 in 10 people 10% risk 3-fold lower risk, assuming the population risk is 3 in 10 3 students in your class (of 30)

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