PLAC4 and beta-HCG mRNA levels are not altered in the maternal circulation of pregnancies with trisomy 21.
OBJECTIVE
Beta-human chorionic gonadotropin (HCG) and pregnancy-associated plasma protein (PAPP-A) are placentally produced proteins whose levels are altered in pregnancies with trisomy 21. PLAC4 is located on chromosome 21 and its expression is restricted to the placenta. Here we investigated whether the levels of beta-HCG-, PAPP-A- and PLAC4 mRNA could be able to discriminate pregnancies whose fetus is affected by trisomy 21.


METHODS
Hundred and forty-three blood samples from normal pregnancies and eight samples from trisomic pregnancies were collected. Total RNA was extracted from whole maternal blood, reverse-transcribed and the three mRNAs were quantified by real-time quantitative PCR. Hundred and nine controls were also tested for the serum levels of PAPP-A and HCG proteins.


RESULTS
Beta-HCG and PLAC4 mRNAs were detected in all samples, in higher amounts than in plasma, whereas the detection rate for PAPP-A mRNA was below 10%. The levels of beta-HCG mRNA significantly correlated with the circulatory concentrations of the HCG protein. However, neither beta-HCG- nor PLAC4 mRNAs show a significant difference between cases and controls.


CONCLUSIONS
Maternal blood levels of beta-HCG-, PLAC4- and PAPP-A mRNAs are not useful markers for the screening of pregnancies with trisomy 21 as their concentrations are either not significantly altered (beta-HCG and PLAC4) or too low to be detected (PAPP-A).
Banzola
Irina
I
Laboratory for Prenatal Medicine and Gyn. Oncology, Department of Biomedicine and University Hospital, Basel, Switzerland.
Rusterholz
Corinne
C
Zannoni
Letizia
L
Rizzo
Nicola
N
Zhong
Xiao Yan
XY
Caramelli
Elisabetta
E
Holzgreve
Wolfgang
W
Farina
Antonio
A
Hahn
Sinuhe
S
D016022:Case-Control Studies; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D004314:Down Syndrome / Q000097:blood / Q000235:genetics*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011266:Pregnancy-Associated Plasma Protein-A / Q000096:biosynthesis* / Q000235:genetics; D011296:Prenatal Diagnosis / Q000379:methods*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018997:Chorionic Gonadotropin, beta Subunit, Human; D012333:RNA, Messenger; D011266:Pregnancy-Associated Plasma Protein-A