Genetic Screening Flashcards
1
Q
contrast targeted screening and population screening
A
- targeted screening
- screening of populations known to be at risk
- screening of high risk ethnic groups (Tay-Sach’s, thalassemia)
- identifying persons at risk of having children w/ disease
- population screening
- adult screening that is presymptomatic/predictive
- PAP, breast, prostate
- screening all members of a designated population regardless of family history
- adult screening that is presymptomatic/predictive
2
Q
describe what is looked for in first trimester tests
A
- pregnancy associated plasma protein-A (PAPP-A)
- B-hCG
3
Q
describe what is looked for in second trimester tests
A
- triple test:
- AFP
- estriol
- B-hCG
- quad test:
- inhibin A
4
Q
describe results of first and second trimester screening
A
- trisomy 21 = increased free B-hCG and increased inhibin A
- trisomy 18 = trisomy 13
- neural tube defect = increased AFP
5
Q
describe fetal DNA fragments
A
- fetal DNA fragments are matched to a specific chromosome and researchers tally how many gene fragments originated from each chromosome
- women with Down syndrome had more fetal chromosome 21 fragments in their blood than normal
6
Q
describe nuchal translucency
A
- increased NT thickness associated with chromosome aneuploidy
- trisomy 21, 18. 13. Turner syndrome
7
Q
describe chorionic villus sampling
A
done at 11-12 weeks
- involves removal of fetal cells by aspiration from inner surface of placenta
- direct chromosomal analysis by FISH allows rapid results
8
Q
describe amniocentesis
A
15-18 weeks
- aminiotic fluid aspirated trans-abdominally guided by ultrasound
- fetal cells pelleted by centrifugation and used for chromosome analysis
9
Q
describe criteria for neonatal screening
A
- the disorder produces irreversible damage if untreated early in life
- there is a treatment available for the disorder
- early intervention is effective
- a reliable lab test for detection
10
Q
describe what an amino acid profile from a patient with PKU would look like
A
