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Questions and Answers
What is a characteristic feature of complex diseases in terms of family risk?
What is a characteristic feature of complex diseases in terms of family risk?
Which of the following statements best describes the role of genetics in complex diseases?
Which of the following statements best describes the role of genetics in complex diseases?
In assessing genetic contribution to disorders, what does heritability refer to?
In assessing genetic contribution to disorders, what does heritability refer to?
What is one common approach to estimating genetic contributions to disorders?
What is one common approach to estimating genetic contributions to disorders?
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Which of the following diseases is given as an example of a complex disease?
Which of the following diseases is given as an example of a complex disease?
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Which interaction type is noted as contributing to complex diseases?
Which interaction type is noted as contributing to complex diseases?
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What distinguishes complex diseases from simple genetic disorders?
What distinguishes complex diseases from simple genetic disorders?
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Which genetic disorder is cited as an example of a Mendelian disease?
Which genetic disorder is cited as an example of a Mendelian disease?
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Which factor is NOT mentioned as contributing to complex diseases?
Which factor is NOT mentioned as contributing to complex diseases?
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What is suggested as a potential outcome of understanding the genetics behind complex diseases?
What is suggested as a potential outcome of understanding the genetics behind complex diseases?
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How is the life expectancy of individuals with Cystic Fibrosis characterized?
How is the life expectancy of individuals with Cystic Fibrosis characterized?
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What characterizes the inheritance pattern of Mendelian diseases like Cystic Fibrosis?
What characterizes the inheritance pattern of Mendelian diseases like Cystic Fibrosis?
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What genetic condition is associated with the highest penetrance by age 70?
What genetic condition is associated with the highest penetrance by age 70?
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Which of the following disorders primarily involves rare variants with Mendelian inheritance patterns?
Which of the following disorders primarily involves rare variants with Mendelian inheritance patterns?
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What is the approximate carrier frequency for BRCA1 mutations in European populations?
What is the approximate carrier frequency for BRCA1 mutations in European populations?
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Which of the following represents a complex disease primarily influenced by polygenic factors?
Which of the following represents a complex disease primarily influenced by polygenic factors?
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Which major genes are implicated in breast cancer susceptibility?
Which major genes are implicated in breast cancer susceptibility?
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What is the significance of the P-value threshold of 5e-08 in genetic studies?
What is the significance of the P-value threshold of 5e-08 in genetic studies?
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Which of the following complex diseases is primarily associated with common variants?
Which of the following complex diseases is primarily associated with common variants?
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When did candidate gene association studies begin, according to the historical context provided?
When did candidate gene association studies begin, according to the historical context provided?
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What are polygenic risk scores primarily used for?
What are polygenic risk scores primarily used for?
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Which lifestyle factor is NOT included in the healthy lifestyle score for assessing coronary artery disease risk?
Which lifestyle factor is NOT included in the healthy lifestyle score for assessing coronary artery disease risk?
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How does a high genetic risk score affect CAD risk when coupled with environmental factors?
How does a high genetic risk score affect CAD risk when coupled with environmental factors?
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What significant threshold p-value is commonly used in genome-wide association studies for establishing statistical significance?
What significant threshold p-value is commonly used in genome-wide association studies for establishing statistical significance?
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What does a score of 2 in the environmental risk assessment indicate?
What does a score of 2 in the environmental risk assessment indicate?
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What is the main limitation of genetic and environmental risk factors concerning individual risk predictions for coronary artery disease?
What is the main limitation of genetic and environmental risk factors concerning individual risk predictions for coronary artery disease?
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Which method of genotyping studies began in the 1980s and relied on genetic linkage maps?
Which method of genotyping studies began in the 1980s and relied on genetic linkage maps?
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In the study of coronary artery disease (CAD), how many SNPs were identified as associated with CAD risk?
In the study of coronary artery disease (CAD), how many SNPs were identified as associated with CAD risk?
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Which of the following is true about the relationship between genetic loci and complex diseases?
Which of the following is true about the relationship between genetic loci and complex diseases?
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What does the term 'penetrance' relate to in genetic studies?
What does the term 'penetrance' relate to in genetic studies?
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Which of the following variants were discussed as accounting for a small proportion of the genetic component of CAD?
Which of the following variants were discussed as accounting for a small proportion of the genetic component of CAD?
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What is the primary limitation of SNPs associated with polygenic diseases like CAD?
What is the primary limitation of SNPs associated with polygenic diseases like CAD?
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Which relative risk is associated with high environmental factors and low genetic risk for coronary artery disease?
Which relative risk is associated with high environmental factors and low genetic risk for coronary artery disease?
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What major advancement in genotyping occurred in 2010?
What major advancement in genotyping occurred in 2010?
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In the context of predicting coronary artery disease, what role does a healthy lifestyle play?
In the context of predicting coronary artery disease, what role does a healthy lifestyle play?
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Which of the following represents an accurate description of the relationship between genetics and environmental risks for coronary artery disease?
Which of the following represents an accurate description of the relationship between genetics and environmental risks for coronary artery disease?
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The SNP rs17087335 is significantly associated with CAD. What is the odds ratio indicating its effect on CAD risk?
The SNP rs17087335 is significantly associated with CAD. What is the odds ratio indicating its effect on CAD risk?
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What is the nature of CAD risk according to the identified SNPs?
What is the nature of CAD risk according to the identified SNPs?
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Study Notes
Complex Genetic Disorders
- Complex genetic disorders are influenced by numerous genetic and environmental factors, unlike single-gene disorders.
- Common examples include Alzheimer’s disease, breast cancer, coronary artery disease, and others.
Definitions and Characteristics
- Complex diseases show increased familial risk, but this risk may be modest compared to the general population.
- There is no clear inheritance pattern; multiple genes and environmental interactions play a role.
- Examples include inflammatory bowel disease, depression, multiple sclerosis, and heart disease.
Genetic Contribution Assessment
- Twin studies measure disease concordance in monozygotic vs dizygotic twins to estimate heritability.
- Heritability defines the proportion of trait variance due to genetic factors—schizophrenia has ~80% heritability.
Spectrum of Genetic Variants
- Disorders can range from rare Mendelian disorders to common polygenic conditions influenced by a mix of variants.
- Well-known Mendelian disorders: cystic fibrosis, Huntington’s disease.
- Common disorders include breast cancer (BRCA1, BRCA2), cardiovascular disease, Alzheimer’s, and autism.
Breast Cancer Genetics
- Major genes involved: BRCA1 and BRCA2, with rare mutations in each gene.
- High penetrance: 65% for BRCA1 carriers, 45% for BRCA2 by age 70.
- In Europe, BRCA1 mutation carriers: 1 in 1000; BRCA2 mutation carriers: 1 in 800.
Evolution of Complex Disease Mapping
- Candidate gene studies (1950s), linkage studies (1980s), genome-wide association studies (2005), and next-gen sequencing (2010s) have progressively increased resolution and understanding of genetic influences.
Coronary Artery Disease (CAD)
- A genome-wide association study identified 58 SNPs related to CAD through data from 60,801 cases and 123,504 controls.
- Each SNP contributes slightly to overall risk; effects are cumulative across multiple variants.
- An example SNP (rs17087335) shows an odds ratio of 1.06 for CAD with 21% frequency of the risk allele T.
Polygenic Risk Scores (PRS)
- Over 200 SNPs associated with CAD contribute low-risk profiles, combined for overall assessment.
- PRS show promise but lack robust clinical utility due to incomplete understanding of total heritability and environmental influences.
Interaction of Genetic and Environmental Factors
- Both genetic predisposition and lifestyle choices contribute to CAD risk; a summary score gauges lifestyle (e.g., smoking, diet, exercise).
- Higher genetic risk can be mitigated through healthier choices, while poor environments can elevate risk even in those with low genetic predisposition.
Summary of Key Concepts
- Complex diseases result from interactions of many genetic loci and environmental factors, complicating risk prediction.
- Understanding terms such as penetrance, odds ratios, and relative risk is essential for evaluating complex disease impact.
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Description
Explore the intricacies of complex genetic disorders, which involve multiple genetic and environmental factors. This quiz covers common disorders such as Alzheimer's disease and breast cancer, highlighting their characteristics and the nature of familial risk involved.
