Population Screening for Genetic Disease Flashcards
(20 cards)
What is the primary purpose of screening tests in health care?
To detect treatable human diseases in their presymptomatic stage.
Name two well-known examples of population screening.
- Papanicolaou (Pap) tests for cervical dysplasia
- Screening for hypercholesterolemia
What is the definition of population screening?
Large-scale testing of populations for disease to identify those who probably have the disease and those who probably do not.
What is genetic screening?
Population screening for genetic variants that can cause disease in the carrier or their descendants.
What is an example of newborn screening for inherited metabolic diseases?
Newborn screening for phenylketonuria (PKU).
What is the goal of genetic screening?
Early recognition of a disorder to prevent or reverse the disease process or to make informed reproductive decisions.
What should be considered when deciding on a new screening program?
- Seriousness of the condition
- Commonality of the condition
- Natural history of the disease
- Availability of effective treatment
- Acceptability and ease of the screening test
- Validity and reliability of the test
- Accessibility of resources for diagnosis and treatment
Define sensitivity in the context of screening tests.
The ability of the test to correctly identify those with the disease.
Define specificity in the context of screening tests.
The ability of the test to correctly identify those without the disease.
What is the relationship between sensitivity and specificity?
When sensitivity increases, specificity decreases, and vice versa.
What is the positive predictive value?
The fraction of persons with a positive test result who truly have the disease.
What is the negative predictive value?
The fraction of persons with a negative result who truly do not have the disease.
What is an example of a condition that can be screened for using family screening?
Duchenne muscular dystrophy.
How does tandem mass spectrometry operate?
It uses two mass spectrometers to separate and analyze ionized molecules based on their mass and charge
The first spectrometer separates molecules, while the second assesses the fragments.
What is heterozygote screening?
Testing a target population to identify unaffected carriers of disease-causing mutations
It is often applied to autosomal recessive disorders.
What is the genetic basis of Tay–Sachs disease?
Deficiency of the lysosomal enzyme β-hexosaminidase A (HEX A)
This leads to accumulation of GM2 ganglioside in neuronal lysosomes.
What does presymptomatic diagnosis allow?
Testing at-risk persons for inherited disease-causing mutations before clinical symptoms appear
Examples include Huntington disease and autosomal dominant breast/ovarian cancer.
What are the psychosocial implications of genetic screening?
Anxiety, cost, potential stigmatization, and misunderstandings about test results
Positive screening does not necessarily indicate disease presence.
What are the recommended guidelines for heterozygote screening?
- Screening should be voluntary
- Confidentiality must be ensured
- Requires informed consent
- Adequate education and counseling must be included
- Quality control of laboratory testing is required
Equal access to testing is also emphasized.
What is the role of genetic counseling in genetic screening?
To provide education about risks, testing, and available options
Effective counseling can mitigate misunderstandings and anxiety.
