[1] Univ Connecticut, Dept Genet & Dev Biol, Ctr Hlth, Farmington, CT 06030 USA
[2] Univ Barcelona, Sch Med, Inst Gynecol Obstet & Neonatol, Prenatal Diag Unit,Hosp Clin, Catalonia, Spain
[3] Chinese Univ Hong Kong, Prince Wales Hosp, Dept Chem Pathol, Hong Kong, Hong Kong, Peoples R China
[4] Columbia Univ, Med Ctr, Dept Obstet & Gynecol, New York, NY USA
[5] Univ Penn, Dept Obstet & Gynecol, Philadelphia, PA 19104 USA
[6] Radboud Univ Nijmegen, Med Ctr, Dept Human Genet, NL-6525 ED Nijmegen, Netherlands
[7] Albert Einstein Coll Med, Dept Obstet & Gynecol, New York, NY USA
[8] Univ Calgary, Dept Obstet & Gynecol, Calgary, AB, Canada
[9] Tel Aviv Univ, Sackler Fac Med, Assaf Harofe Med Ctr, Dept Obstet & Gynecol, IL-69978 Tel Aviv, Israel
[10] Stanford Univ, Sch Med, Dept Obstet & Gynecol, Stanford, CA 94305 USA
[11] Washington Univ, Dept Obstet & Gynecol, St Louis, MO USA
[12] Natl Inst Publ Hlth & Environm RIVM, Lab Infect Dis & Perinatal Screening, Bilthoven, Netherlands
[13] King George Hosp, Barking Havering Univ Hosp, Dept Clin Biochem, Prenatal Screening Unit, Goodmayes, England
[14] King George Hosp, Redbridge Univ Hosp, Dept Clin Biochem, Prenatal Screening Unit, Goodmayes, England
[15] North York Gen Hosp, Genet Program, Toronto, ON, Canada
[16] Univ Plymouth, Dept Math & Stat, Plymouth PL4 8AA, Devon, England
[17] Sourasky Med Ctr, Genet Inst, Prenatal Diag Unit, Tel Aviv, Israel