title: Atypicality revisited: further data on the effectiveness of the Mahalanobis distance in Down's syndrome screening.
abstract: Further data suggesting that assessment of atypicality may be a valuable addition to Down's syndrome screening is presented, based on results from 1521 unaffected pregnancies and 190 chromosomally abnormal pregnancies. For a 1% increase in false positive rates (over the Down's screening-related false positives), it is estimated that the detection of non-trisomy 21 abnormalities may be enhanced by approximately 40%. These false positive and detection rates are similar to previous reports for specific trisomy 18 screens. Further work is necessary to prove whether a specific trisomy 18 screen, or an atypicality screen is preferable.
authors.affiliation: Clinical Chemistry Department, Burton Hospital, Burton upon Trent, UK.
authors.forename: T M
authors.initials: TM
authors.lastname: Reynolds
mesh_terms: D002869:Chromosome Aberrations / Q000175:diagnosis*; D025063:Chromosome Disorders; D004314:Down Syndrome / Q000175:diagnosis / Q000235:genetics*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D015999:Multivariate Analysis; D011247:Pregnancy; D011296:Prenatal Diagnosis