Genetic Screening Flashcards Preview

ER Biochem > Genetic Screening > Flashcards

Flashcards in Genetic Screening Deck (10):

contrast targeted screening and population screening

  • 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


describe what is looked for in first trimester tests

  • pregnancy associated plasma protein-A (PAPP-A)
  • B-hCG


describe what is looked for in second trimester tests

  • triple test:
    • AFP
    • estriol
    • B-hCG
  • quad test:
    • inhibin A 


describe results of first and second trimester screening

  • trisomy 21 = increased free B-hCG and increased inhibin A
  • trisomy 18 = trisomy 13
  • neural tube defect = increased AFP

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describe fetal DNA fragments

  • 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


describe nuchal translucency

  • increased NT thickness associated with chromosome aneuploidy
    • trisomy 21, 18. 13. Turner syndrome


describe chorionic villus sampling

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


describe amniocentesis

15-18 weeks

  • aminiotic fluid aspirated trans-abdominally guided by ultrasound
  • fetal cells pelleted by centrifugation and used for chromosome analysis


describe criteria for neonatal screening

  • 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 


describe what an amino acid profile from a patient with PKU would look like

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