BRCA1 and BRCA2 Mutations Quiz

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Questions and Answers

What is the primary role of BRCA1 and BRCA2 in inherited breast cancer?

Promoting tumor growth

Repairing DNA double-strand breaks (correct)

Increasing estrogen production

Regulating hormone levels

What is the percentage chance of a woman with one copy of a BRCA1 mutation developing breast cancer?

60%

50%

80% (correct)

70%

Which of the following options is NOT one of the strategies for managing BRCA mutations?

Tamoxifen for preventing growth of residual cancer cells

Genetic testing for early intervention

Increased exposure to carcinogens (correct)

Prophylactic surgeries like mastectomy

Which medical intervention uses PARP inhibitors?

Further damaging cancer cells' ability to repair DNA Signup and view all the answers

What does LOH stand for in the context of BRCA mutations?

Loss of Heterozygosity Signup and view all the answers

Which type of breast surgery removes only the tumor?

Both B and C Signup and view all the answers

How do BRCA mutations primarily affect genetic outcomes?

By increasing the risk of cancer due to compromised DNA repair Signup and view all the answers

How is preimplantation genetic diagnosis (PGD) utilized?

To screen embryos for BRCA mutations during IVF Signup and view all the answers

What is the approximate percentage of breast cancer cases accounted for by BRCA1 and BRCA2 mutations?

15% Signup and view all the answers

Which of the following statements is true regarding women with BRCA2 mutations?

Not all women with BRCA2 mutations develop cancer. Signup and view all the answers

What is the purpose of using radiation therapy after surgery?

To ensure no cancer cells remain Signup and view all the answers

Which screening method has been proven effective at reducing mortality?

Colonoscopy Signup and view all the answers

What genetic mutation is primarily associated with Familial Adenomatous Polyposis (FAP)?

APC gene mutation Signup and view all the answers

What characteristic differentiates Hereditary Non-Polyposis Colon Cancer (HNPCC) from other types of colon cancer?

It is characterized by earlier onset and rapid progression Signup and view all the answers

Which of the following statements about inherited colon cancer is accurate?

5% of colon cancers are inherited Signup and view all the answers

Which gene is commonly mutated in HNPCC cases?

hMLH1 Signup and view all the answers

What is a common outcome of radiation therapy in patients?

Long-term lung cell damage Signup and view all the answers

What is the typical follow-up mutation pathway in colon cancer progression?

APC → ras → tumor suppressor → p53 → oncogenes Signup and view all the answers

What is one method through which polyps can be removed during screening?

During a colonoscopy Signup and view all the answers

How does the inheritance pattern of HNPCC appear due to the likelihood of a second mutation?

Autosomal dominant inheritance Signup and view all the answers

Study Notes

BRCA1 and BRCA2 Mutations and Inherited Breast Cancer

BRCA1 and BRCA2 are genes involved in DNA repair mechanisms, specifically in repairing double-strand breaks.
Loss of heterozygosity (LOH) occurs when the wild-type allele of BRCA1 is deleted or inactivated.
In sporadic cases, both alleles are lost.
Somatic cells inherit a first BRCA mutation, resulting in heterozygotes.
The loss of the second allele is more likely in these cells, transforming them into homozygous mutant cells.
An 80% penetrance of breast cancer occurs in individuals with one mutated allele, meaning that individuals with a BRCA mutation have an 80% chance of developing breast cancer.
Individuals with one mutated allele have 80% chance of developing breast cancer.
The other BRCA gene or PARP can compensate for the loss of one BRCA gene, with BRCA1 carriers having an earlier onset of disease.

Options for BRCA Positive Mutations

Genetic testing allows for early intervention and better treatment options.
Individuals can reduce exposure to cancer-promoting environments or undergo prophylactic surgeries to remove breasts or ovaries.
Tamoxifen, a medication, can be used to prevent the growth of remaining tumor cells after breast cancer surgery.
It is also taken by individuals with BRCA mutations who have not yet developed cancer.
Preimplantation genetic diagnosis (PGD) can be used for women with germline mutations.
Embryos can be screened during in vitro fertilization for BRCA mutations, allowing for the selection of mutation-free embryos.
PARP inhibitors further damage DNA repair, leading to cell death due to too many mutations.

Other Genes and Breast Cancer Risk

BRCA1 and BRCA2 account for 15% of breast cancer cases. 5% of other gene mutations can also be associated with breast cancer.

Breast Removal Surgery

Radical mastectomy, which removes the breast, lymph nodes, and chest muscles, is not necessary in most cases.
Partial mastectomy (lumpectomy) is the standard approach, removing only the tumor.
Radiation therapy is used following the procedure to ensure no cancer cells spread or are left behind.
Metastatic cancer cannot be surgically removed.

Cancer Screening and Prevention

Screening aims to prevent advanced cancer and reduce mortality.
Screening has not significantly reduced mortality in breast and ovarian cancers, as it can find cancers that are not progressive, leading to unnecessary interventions.
Lung cell damage can occur in those treated with radiation.
PSA tests and colonoscopy are good methods of screening.
Polyps can be removed in the doctor's office.
Screening for colon cancer is proven effective in reducing mortality.

Inherited Colon Cancer

Most colon cancers are sporadic, with only 5% being inherited.
There are two forms of inherited colon cancer:
- Familial Adenomatous Polyposis (FAP)
- Hereditary Non-Polyposis Colon Cancer (HNPCC)

Familial Adenomatous Polyposis (FAP)

Due to a germline mutation in the APC gene.
Leads to hundreds of polyps in the colon, one of which can become cancerous with additional mutations.
The APC gene is involved in signal transduction and cell cycle stability.
Mutations accumulate in cells with this germline mutation.
Colon cancer progression involves mutations in:
- APC -> ras -> Tumor suppressor -> p53 -> Oncogenes

Hereditary Non-Polyposis Colon Cancer (HNPCC)

Due to germline mutations in DNA repair genes.
Characterized by:
- Earlier onset (45 vs. 65 in the general population)
- 80% infected (vs. 64% in the general population)
- Rapid progression from benign to malignant tumors.
60% of HNPCC cases involve mutations in hMLH1.
35% of cases note mutations in hMSH2.
Follows the two-hit model.
- One altered gene is inherited in the germline, and the second mutation occurs later (LOH).
Loss of heterozygosity (LOH) at hMLH1 or hMSH2 is linked to tumor development.
HNPCC is autosomal recessive, but it appears autosomal dominant due to the high chance of a second mutation.

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Description

This quiz explores the role of BRCA1 and BRCA2 genes in inherited breast cancer. It covers genetic mechanisms, mutation effects, and the implications of testing for BRCA mutations. Test your knowledge on the genetics of breast cancer and the significance of these mutations in disease progression.