PAPPA and trisomy 21: Notable features of Table 1 are the strong positive correlations between log MoM ADAM12-S and log MoM PAPP-A in the control pregnancies, with minimal variation across gestational age, and the significant positive correlation (r = 0.33, P < 0.03) between log MoM ADAM12-S and log MoM PAPP-A in trisomy 21 pregnancies.