Lect 12 - Genetic Screening and Counseling Flashcards
What is the difference between targeted and population screening?
Targeted screening is more specific screening in ethnic groups, possible high risk carriers, etc. Population screening is prenatal/newborn screening for common genetic disorders found in general population.
What are four major genetic disorders tested for prenatally?
1) Trisomy 21 (Down syndrome)
2) Trisomy 18 (Edward syndrome)
3) Trisomy 13 (Patau syndrome)
4) Neural tube defects
What are two non-invasive prenatal genetic screening modalities?
1) maternal serum
2) ultrasound
What is looked for on ultrasound to diagnose neural tube defects?
Nuchal translucency
What are two invasive prenatal genetic screens?
1) amniocentesis
2) Chorionic Villus sampling
What are the two proteins sampled for in the first trimester in the maternal serum?
1) PAPP-A
2) beta-hCG
What are the four proteins sampled for in the second trimester in the maternal serum?
1) alpha-fetoprotein
2) estriol
3) beta-hCG
4) inhibin A
What two neural tube defects is AFP increased in? What disorder is it decreased?
Increased in open spina bifida and anencephaly. Decreased in Down syndrome.
There is an increase in the amount of cfDNA (cell free DNA) or fetal DNA fragments in which genetic disorder?
Down Syndrome
What are some features seen on ultrasound in genetic disorders and what is the specific disorder it indicates?
Rocker bottom feet = Trisomy 18 Micrognathia = cri-du-chat Anencephaly = Neural tube defect Nasal bone hypoplasia = Down Syndrome Enlarged nuchal translucency = Chromosomal aneuploidy
When is chorionic villus sampling done?
11-12 weeks
What genetic test is done in chorionic villus sampling?
FISH
When is amniocentesis done?
15-18 weeks
When can percutaneous umbilical blood sampling be done?
18 weeks
What are the week marks for first, second, and third trimester?
1) week 1-12
2) week 13-26
3) week 27-40
