Maternal serum ADAM12 is reduced, on average, in early first-trimester Down and Edwards' syndrome pregnancies but the extent of reduction declines with gestation. Here we study levels at 9-12 weeks when the marker might be used concurrently with other established markers.Methods
Samples from 16 Down and 2 Edwards' syndrome cases were retrieved from storage and tested together with 313 unaffected singleton pregnancies using a semi-automated time-resolved immuno-fluorometric assay. Results were expressed in multiples of the gestation-specific median (MoM) based on regression.Results
The median in Down syndrome was 0.94 MoM with a 10th-90th centile range of 0.22-1.63 MoM compared with 1.00 and 0.33-2.24 MoM in unaffected controls (P = 0.21, one-side Wilcoxon Rank Sum Test). The two Edwards' syndrome cases had values 0.31 and 2.17 MoM.Conclusions
ADAM12 cannot be used concurrently with other markers in the late first trimester. However, it does have the potential to be used earlier in pregnancy either concurrently with other early markers or in a sequential or contingent protocol. More data will be required to reliably predict the performance of either approach.