title: Absence of nasal bone and detection of trisomy 21.
authors.forename: David J R
authors.initials: DJ
authors.lastname: Hutchon
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D009295:Nasal Bone / Q000002:abnormalities*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012306:Risk