title: Where have all the trisomies gone?
abstract: Providing reliable prenatal screening performance estimates is critical for patient counseling and policy-making. Women who choose prenatal screening for aneuploidy are likely to be concerned not only with the common aneuploidies but with all causes of intellectual disability and serious birth defects. Sequential prenatal screening (combined serum and ultrasound testing) for aneuploidy detection commonly is offered as a primary screening test. Among women identified as screen positive, cell-free (cf)DNA has been added recently as a secondary, noninvasive screening option, before the consideration of invasive diagnostic testing (eg, amniocentesis and karyotype). With the anticipation of lower costs in the future, cfDNA might be an alternative to sequential screening in the general population. Sequential and cfDNA tests are both noninvasive, and both identify common aneuploidies. Screening via cfDNA detects more common chromosome abnormalities (eg, trisomy 21, sex trisomies). Sequential screening can identify other aneuploidies (eg, triploidy), as well as chromosome abnormalities associated with fetal structural abnormalities. When the advantages and disadvantages of routine sequential screening with routine cfDNA screening are compared, one important measure is the proportion and severity of chromosome abnormalities identified. When reporting these detection rates, authors need to carefully consider the impact of multiple well-described biases. For women to make informed choices in situations of this type, determining reliable comparative performance estimates is crucial.
authors: Department of Pathology and Laboratory Medicine, Women & Infants Hospital, Providence, RI.
authors: Glenn E
authors: GE
authors: Palomaki
authors: Department of Pathology and Laboratory Medicine, Women & Infants Hospital, Providence, RI.
authors: Geralyn M
authors: GM
authors: Lambert-Messerlian
authors: Department of Pathology and Laboratory Medicine, Women & Infants Hospital, Providence, RI.
authors: James E
authors: JE
authors: Haddow
mesh_terms: D000649:Amniocentesis; D002869:Chromosome Aberrations; D025063:Chromosome Disorders / Q000175:diagnosis*; D004247:DNA / Q000097:blood; D003657:Decision Making; D005260:Female; D006801:Humans; D007621:Karyotyping; D062145:Maternal Serum Screening Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012680:Sensitivity and Specificity; D012729:Sex Chromosome Aberrations; D014314:Trisomy; D016216:Ultrasonography, Prenatal
chemical_list: D004247:DNA
keywords: Down syndrome; biases; cell-free DNA; detection rate; patient preference; sequential screening; sex chromosome trisomies