Placental protein 13 as a first trimester screening marker for aneuploidy

Abstract

Objective: To determine whether Placental Protein 13 (PP13) could be an additional marker in first trimester screening for aneuploidies.

Methods: To evaluate differences in multiples of the gestation-specific normal median (MoMs), PP13 concentrations were measured in serum samples from Down syndrome, trisomy 18 and 13 affected pregnancies and euploid singleton pregnancies (four for each case matched for duration of storage, maternal weight and age).

Results: The PP13 MoM in Down syndrome cases (n = 153) was 0.91 [not statistically significant from controls (n = 853); P = 0.06; Wilcoxon rank sum test, two-tail]. PP13 MoMs were decreased in trisomy 18 (n = 38-median MoM 0.64; P < 0.0001) and trisomy 13 cases (n = 23-median MoM 0.46; P < 0.0001). There was a slight upward trend in MoM values of the Down syndrome cases with gestational weeks. The PP13 MoM was significantly correlated with the pregnancy associated plasma protein-A MoM and the free beta-subunit of human chorion gonadotrophin (fbeta-hCG) MoM.

Conclusion: PP13 does not seem to be a good marker for Down syndrome. PP13 MoMs are, however, significantly lower in trisomy 18 and 13 pregnancies. The addition of PP13 to the current screening test could be valuable for improving the discrimination of aneuploid from euploid pregnancies.