Genetics week 16 Flashcards
Name the three key considerations for a screening program
- Disease characteristics
-Test characteristics
-Healthcare system considerations
Explain disease characteristics as a key consideration for a screening program(3)
- The disease should be serious and relatively common to justify screening costs.
-The natural history should be well understood.
-An effective treatment or prenatal diagnosis should be available.
Explain the test characteristics as a key consideration for a screening program (3)
The test should be :
- Acceptable
-Easy to perfrom and inexpensive
- Should be accurate and reliable
Explain the healthcare system considerations as a key consideration for screening
- Resources for diagnosis and treatment must be accessible.
Effective communication of results should be ensured.
Name the 2 parts of a screening process
Initial test
Follow up test
Explain the inital test of a screening program
Inexpensive, applied to a broad population
Explain the follow up test of a screening program
More accurate, expensive, and time-consuming, applied to those at risk
What is sensitivity
-The ability to correctly identify those with the disease
- (True positives)
What is specificity
- The ability to correctly identify those without the disease (True Negatives)
What does a higher sensitivity mean
- More false positives
What does a higher specificty mean
-More false negatives
What is PPV , Positive predictive Value
Proportion of positive tests that are true positives.
What is NPV, Negative predictive value
Porportion of negative tests that are true negatives
What is the purpose of Newborn screening
-Early detection and prevention of genetic diseases
Give examples of disorders newborns are screened for(5)
Phenylketonuria(PKU) , galactosemia, hypothyroidism, Hemoglobin disorders, duchenne muscular dystrophy
What technique is used to screen newborns for metabolic disorders
- Tandem mass spectrometry
Describe the relationship between sensitivity and specificity
- Inversely porportional
What is the definition and purpose of Heterozygote screening
-Identifies unaffected carriers of autosomal recessive disease-causing mutations.
-Helps at-risk individuals understand their reproductive risks and options
Give examples of heterozygote screening
- Tay-Sachs Disease in jewish population
- Beta Thalassemia in ethnic groups
- Cystic Fibrosis
Name the ethical and legal considerations in heterozygote screening
- Informed consent and genetic counselling are essential
- Screening must be voluntary with confidentiality
Name all the limitations of genetic testing (4)
-No Test is 100% Accurate
Errors can occur due to mosaicism or genotyping
-Genetic Testing Detects Mutations, Not Disease.
Many mutations have incomplete penetrance (not everyone with the mutation develops the disease).
-Tests May Not Detect All Disease-Causing Mutations
- Risk of discrimination
What is α1-Antitrypsin (AAT) Deficiency
An autosomal recessive disorder amongs whites
What does α1-Antitrypsin (AAT) Deficiency lead to
-lung damage (emphysema) and liver cirrhosis.
What is the function of α1-Antitrypsin (AAT)
serine protease inhibitor, primarily protecting lung tissue from neutrophil elastase.
Name the 2 test to diagnose α1-Antitrypsin (AAT) Deficiency
- Inital test
-Confirmatory test
Explain what does the inital test measure to diagnose α1-Antitrypsin (AAT) Deficiency
Measures serum AAT concentration (low levels suggest deficiency).
Name the 2 confirmatory test measure to diagnose α1-Antitrypsin (AAT) Deficiency
-Protein electrophoresis
-DNA testing for SERPINA1 mutations
