title: [Prenatal diagnosis of trisomy 21].
abstract: Trisomy 21 is the most frequent chromosome anomaly found in the living newborns. Prenatal diagnosis by amniocentesis was limited until recently to older pregnant women. Maternal blood biochemical markers (alpha-fetoprotein, unconjugated estriol, human chorionic gonadotropin) and ultrasonographic signs (nuchal fold thickening, femur length to biparietal diameter ratio) can discriminate a group of higher-risk women even though they are not aged. Numerous factors need to be considered when establishing such a screening program including pre-analytical variables (gestational age, diabetes, smoking, race), analytical variables (choice of reagents, quality control) or post-analytical (result reporting, follow-up of abnormal results). Until now the study of these markers has been restricted to the second trimester but they could become useful earlier during pregnancy.
authors.affiliation: Centre de Recherche, Hôpital Saint-François d'Assise, Québec, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Massé
authors.forename: J C
authors.initials: JC
authors.lastname: Forest
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D004964:Estriol / Q000097:blood; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D016216:Ultrasonography, Prenatal; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004964:Estriol
vernacular_title: Dépistage prénatal de la trisomie 21.