34 Questions
What is the purpose of a screening test in individuals with a family history of a particular disease?
To identify inherited mutations before symptoms develop
Which of the following is an example of a condition that may be eligible for screening?
Hereditary Breast and Ovarian Cancer syndrome (HBOC)
What percentage of women with breast cancer have germline mutations in BRCA1 or BRCA2?
3% to 4%
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
What is the estimated risk of breast cancer in individuals with a BRCA1 mutation?
80%
What is the estimated risk of ovarian cancer in individuals with a BRCA2 mutation?
30% to 40%
What is the primary purpose of preimplantation genetic diagnosis (PGD)?
To detect mutations in heterozygous individuals
What is the main goal of newborn screening programs?
To identify metabolic disorders in neonates
What is the purpose of isolating a cell in PGD?
To perform diagnostic testing
What is the significance of heterozygous individuals in the context of PGD?
They are at risk of passing on a genetic mutation
What is the result of a defective enzyme in Inborn Errors of Metabolism (IEM) disorders?
A buildup of toxic substances in the body
What is the outcome if an embryo is found to have a genetic mutation in PGD?
The embryo is terminated
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
What is the name of the genetic disorders caused by defects in enzymes?
Inborn Errors of Metabolism (IEM) disorders
What is the primary consequence of a loss of function mutation in Gene B?
Enzyme B is not produced
What happens to Compound 2 in the abnormal metabolic pathway?
It accumulates
What is the significance of early diagnosis and treatment in IEM disorders?
It can prevent complications and improve outcomes
What is the outcome if an IEM disorder is not diagnosed and treated early?
It can be fatal
What is the role of Enzyme B in the normal metabolic pathway?
It converts Compound 2 to Compound 3
What is the consequence of a loss of function mutation in Gene B on the metabolic pathway?
The pathway is disrupted
What is the primary characteristic of IEM disorders?
There is no cure, but they can be managed
What is the purpose of newborn screening for IEM disorders?
To identify the disorder early in newborns
What is the principle that may be compromised in genetic testing due to the shared genetic information with biological relatives?
Autonomy
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
What is the law that protects genetic data in the kingdom?
Personal Data Protection Law
What is the risk of the father being a carrier of Huntington's disease in the scenario described?
50%
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
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
What is the primary source of DNA used for genetic analysis in Non-Invasive Prenatal Testing (NIPT)?
Maternal blood
What is the risk of miscarriage associated with Chorionic Villus Sampling (CVS)?
About 1:600 risk
At what week of pregnancy is Percutaneous Umbilical Blood Sampling (PUBS) typically performed?
18 weeks or later
What is the main difference between invasive and non-invasive prenatal tests?
The type of sample collected
What is the primary condition that Non-Invasive Prenatal Testing (NIPT) is used for?
Chromosomal abnormalities
What is required to confirm a positive result from Non-Invasive Prenatal Testing (NIPT)?
An invasive prenatal test
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.
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.
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