RT Journal Article SR Electronic T1 Prenatal Diagnosis and Screening JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 710 OP 710 DO 10.1136/jmg.30.8.710-a VO 30 IS 8 A1 Alan Emery YR 1993 UL http://jmg.bmj.com/content/30/8/710.2.abstract AB