Lecture 26&27

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What is the purpose of a screening test in individuals with a family history of a particular disease?

To diagnose the disease after symptoms have developed

To develop a treatment plan for the disease

To determine the age of onset of the disease

To identify inherited mutations before symptoms develop (correct)

Which of the following is an example of a condition that may be eligible for screening?

Alzheimer's disease

Hereditary Breast and Ovarian Cancer syndrome (HBOC) (correct)

Diabetes

Hypertension

What percentage of women with breast cancer have germline mutations in BRCA1 or BRCA2?

5% to 6%

1% to 2%

10% to 15%

3% to 4% (correct)

What is the estimated reduction in risk of breast cancer with early detection and prevention in individuals with a BRCA1 or BRCA2 mutation?

90% reduction Signup and view all the answers

What is the estimated risk of breast cancer in individuals with a BRCA1 mutation?

80% Signup and view all the answers

What is the estimated risk of ovarian cancer in individuals with a BRCA2 mutation?

30% to 40% Signup and view all the answers

What is the primary purpose of preimplantation genetic diagnosis (PGD)?

To detect mutations in heterozygous individuals Signup and view all the answers

What is the main goal of newborn screening programs?

To identify metabolic disorders in neonates Signup and view all the answers

What is the purpose of isolating a cell in PGD?

To perform diagnostic testing Signup and view all the answers

What is the significance of heterozygous individuals in the context of PGD?

They are at risk of passing on a genetic mutation Signup and view all the answers

What is the result of a defective enzyme in Inborn Errors of Metabolism (IEM) disorders?

A buildup of toxic substances in the body Signup and view all the answers

What is the outcome if an embryo is found to have a genetic mutation in PGD?

The embryo is terminated Signup and view all the answers

What is the name of the program that screens all babies for conditions that could be life-threatening if not treated early?

Newborn screening program Signup and view all the answers

What is the name of the genetic disorders caused by defects in enzymes?

Inborn Errors of Metabolism (IEM) disorders Signup and view all the answers

What is the primary consequence of a loss of function mutation in Gene B?

Enzyme B is not produced Signup and view all the answers

What happens to Compound 2 in the abnormal metabolic pathway?

It accumulates Signup and view all the answers

What is the significance of early diagnosis and treatment in IEM disorders?

It can prevent complications and improve outcomes Signup and view all the answers

What is the outcome if an IEM disorder is not diagnosed and treated early?

It can be fatal Signup and view all the answers

What is the role of Enzyme B in the normal metabolic pathway?

It converts Compound 2 to Compound 3 Signup and view all the answers

What is the consequence of a loss of function mutation in Gene B on the metabolic pathway?

The pathway is disrupted Signup and view all the answers

What is the primary characteristic of IEM disorders?

There is no cure, but they can be managed Signup and view all the answers

What is the purpose of newborn screening for IEM disorders?

To identify the disorder early in newborns Signup and view all the answers

What is the principle that may be compromised in genetic testing due to the shared genetic information with biological relatives?

Autonomy Signup and view all the answers

What is the implication of a positive pre-symptomatic test result for Huntington's disease on immediate family members?

It may have a major impact on close relatives who may not wish to know their disease status Signup and view all the answers

What is the law that protects genetic data in the kingdom?

Personal Data Protection Law Signup and view all the answers

What is the risk of the father being a carrier of Huntington's disease in the scenario described?

50% Signup and view all the answers

What is the problem raised by the young man's request for pre-symptomatic testing for Huntington's disease?

How to honor his request without unintentionally testing his father Signup and view all the answers

What can be inferred from a positive pre-symptomatic test result for Huntington's disease in the young man?

His father is a carrier of the disease Signup and view all the answers

What is the primary source of DNA used for genetic analysis in Non-Invasive Prenatal Testing (NIPT)?

Maternal blood Signup and view all the answers

What is the risk of miscarriage associated with Chorionic Villus Sampling (CVS)?

About 1:600 risk Signup and view all the answers

At what week of pregnancy is Percutaneous Umbilical Blood Sampling (PUBS) typically performed?

18 weeks or later Signup and view all the answers

What is the main difference between invasive and non-invasive prenatal tests?

The type of sample collected Signup and view all the answers

What is the primary condition that Non-Invasive Prenatal Testing (NIPT) is used for?

Chromosomal abnormalities Signup and view all the answers

What is required to confirm a positive result from Non-Invasive Prenatal Testing (NIPT)?

An invasive prenatal test Signup and view all the answers

Study Notes

Genetic Testing and Screening

Genetic testing can identify mutations before symptoms appear, allowing for early detection and prevention of diseases.
Eligibility for genetic testing includes those with a family history of the disease.

Hereditary Breast and Ovarian Cancer (HBOC)

HBOC is caused by germline mutations in BRCA1 or BRCA2, increasing the risk of breast and ovarian cancer.
BRCA1 mutation increases breast cancer risk by 80% and ovarian cancer risk by 50%.
BRCA2 mutation increases breast cancer risk by 50% and ovarian cancer risk by 30%.

Pre-implantation Genetic Diagnosis (PGD)

PGD is a genetic test on embryos created through in vitro fertilization to detect inherited diseases.
The test can identify mutations in embryos, allowing for selection of unaffected embryos for implantation.
PGD is available in the Kingdom of Saudi Arabia (KSA).

Newborn Screening

Newborn screening programs test for life-threatening conditions that can be treated if detected early.
Inborn Errors of Metabolism (IEM) disorders can be detected through newborn screening.
IEM disorders are caused by defects in enzymes that break down food, leading to toxic substance buildup in the body.

Prenatal Screening

Invasive tests: amniocentesis, chorionic villus sampling (CVS), and percutaneous umbilical blood sampling (PUBS).
Non-invasive tests: non-invasive prenatal testing (NIPT) uses cell-free DNA in maternal blood to detect chromosomal abnormalities.
NIPT is not diagnostic; positive results require confirmation with invasive tests.

Ethical Considerations

Genetic testing raises autonomy concerns, as test results can impact biological relatives who may not wish to know their disease status.
Pre-symptomatic testing can have significant implications for immediate family members, highlighting the need for careful consideration of testing and disclosure.

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This quiz covers genetic screening tests for inherited diseases, such as Hereditary Breast and Ovarian Cancer syndrome and Huntington Disease, that can identify mutations before symptoms appear.