Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

19. Cancer Genetics

Cancer Mutations

Genetics

19. Cancer Genetics

Cancer Mutations

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2:07 minutes

Problem C.8a

Textbook Question

The inheritance of certain mutations of BRCA1 can make it much more likely that a woman will develop breast or ovarian cancer in her lifetime. Can you say with certainty that a woman inheriting a mutation of BRCA1 will definitely develop breast or ovarian cancer in her lifetime? Why or why not?

Verified step by step guidance

Understand that inheriting a mutation in the BRCA1 gene increases the risk of developing breast or ovarian cancer, but it does not guarantee that cancer will develop. This is because BRCA1 mutations are considered risk factors, not deterministic causes.

Recognize the concept of penetrance in genetics, which refers to the proportion of individuals with a particular genetic mutation who actually express the associated trait or disease. BRCA1 mutations have incomplete penetrance.

Consider environmental factors, lifestyle, and other genetic factors that can influence whether a woman with a BRCA1 mutation will develop cancer. These factors interact with the mutation to affect cancer risk.

Note that genetic counseling and testing provide probabilities or risk assessments rather than certainties, reflecting the complex nature of gene-environment interactions.

Summarize that while a BRCA1 mutation significantly raises the likelihood of cancer, it is not a definitive predictor, so a woman inheriting the mutation may or may not develop breast or ovarian cancer during her lifetime.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

BRCA1 Gene and Its Role

BRCA1 is a gene that produces proteins responsible for repairing DNA damage. Mutations in BRCA1 can impair this repair process, increasing the risk of developing breast and ovarian cancers. However, not all mutations have the same effect, and the presence of a mutation raises risk but does not guarantee cancer.

Genetic Penetrance

Penetrance refers to the proportion of individuals with a specific genetic mutation who actually express the associated trait or disease. In the case of BRCA1 mutations, penetrance is incomplete, meaning some women with the mutation may never develop cancer, while others do, due to various genetic and environmental factors.

Risk Factors and Multifactorial Inheritance

Cancer development is influenced by multiple factors beyond a single gene mutation, including lifestyle, environment, and other genetic variations. Thus, inheriting a BRCA1 mutation increases risk but does not act alone, making cancer a multifactorial disease where risk is probabilistic, not deterministic.

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The inheritance of certain mutations of BRCA1 can make it much more likely that a woman will develop breast or ovarian cancer in her lifetime. In addition to inheriting a BRCA1 mutation, what else must happen for a woman to develop breast or ovarian cancer?

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Go to the website http://www.cancer.gov and select 'Cancer Types' on the top menu bar. Scroll down to 'Breast Cancer' and click. Select 'Cases & Prevention' from the options. Click 'More information' and select 'BRCA Mutations: Cancer Risk and Genetic Testing'. Use the information on this page to answer the following questions. Are there measures a woman with a positive result can take to lessen her chances of developing cancer or to catch a cancer early in its development?

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Go to the website http://www.cancer.gov and select 'Cancer Types' on the top menu bar. Scroll down to 'Breast Cancer' and click. Select 'Cases & Prevention' from the options. Click 'More information' and select 'BRCA Mutations: Cancer Risk and Genetic Testing'. Use the information on this page to answer the following questions. With regard to the results of genetic testing for BRCA1 and BRCA2 mutations, what is meant by a 'positive result'?

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