• Prenatal screening;
  • first trimester;
  • Monte Carlo simulation



ADAM12 has been shown to be an efficient maternal serum marker for Down syndrome (DS) in the first trimester; but recent studies, using a second generation assay, have not confirmed these findings. We examined the efficiency of a second generation assay for ADAM12.

Materials and Methods

ADAM12 concentrations were determined in 28 first trimester DS and 503 control pregnancies using a novel Research DelfiaR ADAM12 kit. Log10MoM distributions of ADAM12 and correlations with other markers were established. Population performance of screening was estimated by Monte Carlo simulation.


ADAM12 was significantly reduced in the first trimester in DS pregnancies with a log10MoM of −0.1621 (equivalent to 0.68 MoM) (p < 0.001). The reduction decreased with advancing gestational age. ADAM12 used with PAPP-A + hCGβ + NT (CUB screening) increased the detection rate (DR) from 86% to 89% for a false positive rate (FPR) of 5%. When used for a fixed DR of 90%, the addition of ADAM12 resulted in a 25% reduction of the FPR.


ADAM12 is a moderately effective DS marker. It is not a cost-effective addition to CUB screening, but may be used to reduce the FPR in selected high-risk cases. Copyright © 2009 John Wiley & Sons, Ltd.