Genetics week 16

Question 1

Name the three key considerations for a screening program

Answer 1

• Disease characteristics
  -Test characteristics
  -Healthcare system considerations

Question 2

Explain disease characteristics as a key consideration for a screening program(3)

Answer 2

• 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.

Question 3

Explain the test characteristics as a key consideration for a screening program (3)

Answer 3

The test should be :
- Acceptable
-Easy to perfrom and inexpensive
- Should be accurate and reliable

Question 4

Explain the healthcare system considerations as a key consideration for screening

Answer 4

• Resources for diagnosis and treatment must be accessible.
  Effective communication of results should be ensured.

Question 5

Name the 2 parts of a screening process

Answer 5

Initial test
Follow up test

Question 6

Explain the inital test of a screening program

Answer 6

Inexpensive, applied to a broad population

Question 7

Explain the follow up test of a screening program

Answer 7

More accurate, expensive, and time-consuming, applied to those at risk

Question 8

What is sensitivity

Answer 8

-The ability to correctly identify those with the disease
- (True positives)

Question 9

What is specificity

Answer 9

• The ability to correctly identify those without the disease (True Negatives)

Question 10

What does a higher sensitivity mean

Answer 10

• More false positives

Question 11

What does a higher specificty mean

Answer 11

-More false negatives

Question 12

What is PPV , Positive predictive Value

Answer 12

Proportion of positive tests that are true positives.

Question 13

What is NPV, Negative predictive value

Answer 13

Porportion of negative tests that are true negatives

Question 14

What is the purpose of Newborn screening

Answer 14

-Early detection and prevention of genetic diseases

Question 15

Give examples of disorders newborns are screened for(5)

Answer 15

Phenylketonuria(PKU) , galactosemia, hypothyroidism, Hemoglobin disorders, duchenne muscular dystrophy

Question 16

What technique is used to screen newborns for metabolic disorders

Answer 16

• Tandem mass spectrometry

Question 17

Describe the relationship between sensitivity and specificity

Answer 17

• Inversely porportional

Question 18

What is the definition and purpose of Heterozygote screening

Answer 18

-Identifies unaffected carriers of autosomal recessive disease-causing mutations.
-Helps at-risk individuals understand their reproductive risks and options

Question 19

Give examples of heterozygote screening

Answer 19

• Tay-Sachs Disease in jewish population
• Beta Thalassemia in ethnic groups
• Cystic Fibrosis

Question 20

Name the ethical and legal considerations in heterozygote screening

Answer 20

• Informed consent and genetic counselling are essential
• Screening must be voluntary with confidentiality

Question 21

Name all the limitations of genetic testing (4)

Answer 21

-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

Question 22

What is α1-Antitrypsin (AAT) Deficiency

Answer 22

An autosomal recessive disorder amongs whites

Question 23

What does α1-Antitrypsin (AAT) Deficiency lead to

Answer 23

-lung damage (emphysema) and liver cirrhosis.

Question 24

What is the function of α1-Antitrypsin (AAT)

Answer 24

serine protease inhibitor, primarily protecting lung tissue from neutrophil elastase.

Question 25

Name the 2 test to diagnose α1-Antitrypsin (AAT) Deficiency

Answer 25

- Inital test -Confirmatory test

Question 26

Explain what does the inital test measure to diagnose α1-Antitrypsin (AAT) Deficiency

Answer 26

Measures serum AAT concentration (low levels suggest deficiency).

Question 27

Name the 2 confirmatory test measure to diagnose α1-Antitrypsin (AAT) Deficiency

Answer 27

-Protein electrophoresis -DNA testing for SERPINA1 mutations