Genetics Flashcards
1
Q
which trisomies are discussed at booking appointment?
A
13 (patau syndrome), 18 (edwards syndrome), 21 (downs syndrome)
2
Q
how is trisomy screen done in first trimester?
A
serum markers and nuchal thickness
(free fetal DNA in maternal serum. if there too much chromosome 13/18/21 in the mother’s serum - high risk)
3
Q
what is Non invasive prenatal testing (NIPT) positive predictive value
A
> 90%
4
Q
timing of chorionic villus sampling (CVS) and amniocentesis
A
CVS = 11-14 weeks
Amniocentesis >15 weeks
5
Q
Where does the fetal DNA in mother’s serum come from?
A
the placenta
6
Q
NIPT vs NIPD
A
NIPT is screening
NIPD is diagnostic
