1 Division of Fetal Medicine, Department of Obstetrics and Gynecology and Women's Health, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
2 Natera Inc, San Carlos, CA.
3 Division of Human Genetics, Department of Genetics and Genome Sciences, University of Connecticut Health Center, 236 Farmington Ave., Farmington, CT 06030-3808. Electronic address: benn@uchc.edu.