Time-resolved immunofluorometric assay of pregnancy-associated plasma protein A in maternal serum screening for Down's syndrome in first trimester of pregnancy.
A low maternal serum concentration of pregnancy associated plasma protein-A (MS-PAPP-A) in the first trimester has been suggested as a marker for the presence of a Down's syndrome (DS) fetus. We developed a time-resolved immunofluorometric assay (TrIFMA) for PAPP-A with a sensitivity < 3.9 mIU/l. In the 7-12 gestational weeks interval the median multiples of the median (MoM) was 0.57 (95%-confidence interval; 0.47-0.99) in DS pregnancies (n = 29) and lower than in controls (n = 223) (P < 0.005). The efficiency of MS-PAPP-A alone was evaluated using empirical receiver-operator-characteristics (ROC) and a sensitivity of about 25% was found for a false-positive rate of about 10% in the 7-12 gestational weeks interval. In parameterized ROC analysis a sensitivity of 9% was found for a false-positive rate of 5%. The TrIFMA PAPP-A assay seems to fulfil the quality criteria for an assay to be used in large-scale serum screening for Down's syndrome.
Qin
Q P
QP
Department of Clinical Biochemistry, Statens Seruminstitut, Copenhagen, Denmark.
Nguyen
T H
TH
Christiansen
M
M
Larsen
S O
SO
Nørgaard-Pedersen
B
B
D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D011266:Pregnancy-Associated Plasma Protein-A