[1] Tufts Univ New England Med Ctr, Dept Pediat, Div Maternal Fetal Med, Boston, MA 02111 USA
[2] Tufts Univ, Sch Med, Boston, MA 02111 USA
[3] Tufts Univ New England Med Ctr, Dept Pediat, Div Genet, Boston, MA 02111 USA
[4] Columbia Univ, Coll Phys & Surg, Div Maternal Fetal Med, New York Presbyterian Hosp, New York, NY USA