Inhibin A is now an established second-trimester maternal serum marker of D
own syndrome. Since activin A has a common beta-subunit to inhibin A we eva
luated this substance and its binding protein, follistatin, as potential ma
rkers. We studied 30 affected and 199 unaffected pregnancies at 13-16 weeks
' gestation. There was a statistically significant increase in activin A le
vel among the cases with 8 (27 per cent) exceeding the 90th centile in the
controls, and 6 (20 per cent) above the 95th centile. However, the extent o
f overlap was too great to be of value in screening. There was a small decr
ease in follistatin levels among cases but it did not reach statistical sig
nificance. Copyright (C) 1999 John Wiley gr Sons, Ltd.