Maternal serum activin A and follistatin levels in pregnancies with Down syndrome

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.