Ml. Brizot et al., GENE-EXPRESSION OF HUMAN PREGNANCY-ASSOCIATED PLASMA-PROTEIN-A IN PLACENTA FROM TRISOMIC PREGNANCIES, Placenta, 17(1), 1996, pp. 33-36
Placental pregnancy-associated plasma protein-A (PAPP-A) mRNA expressi
on, placental PAPP-A protein concentration and maternal serum levels o
f PAPP-A were examined in pregnancies affected by trisomy 21 (n=8), tr
isomy 18 (n=7) and 15 normal controls at 12-15 weeks of gestation. The
maternal serum concentration of PAPP-A in the trisomic group of pregn
ancies was significantly lower than in the normal controls. However th
ere were no significant differences between the three groups in PAPP-A
mRNA expression or PAPP-A protein concentration in the placental tiss
ues. There was no significant association between the level of placent
al mRNA and either placental protein or maternal serum PAPP-A concentr
ations in the normal or trisomic pregnancies. There was however a sign
ificant association between placental protein and maternal serum PAPP-
A concentrations in the normal and trisomy 21 pregnancies but not in t
hose affected by trisomy 18. These findings suggest that the decrease
in maternal serum PAPP-A in trisomic pregnancies is due to alterations
in post-translational events such as protein stability, alterations i
n the release mechanism of the protein, impaired protein transport acr
oss the placenta or modified serum stability of PAPP-A. (C) 1996 W. B.
Saunders Company Ltd