Complete trisomy 21 vs translocation Down syndrome: a comparison of modes of ascertainment.
OBJECTIVE
To compare the indications for invasive prenatal testing resulting in the detection of translocation Down syndrome and complete trisomy 21.


METHODS
This case control study was based on a large amniocentesis and chorionic villi samples database (n = 534,795). All specimens with translocation Down syndrome (n = 203) comprised the translocation group and were compared with a maternal age-matched group (4 to 1, n = 812) in which complete trisomy 21 was detected. Women with a normal karyotype were randomly selected (n = 812) and served as controls. Indications for invasive testing were compared among the 3 paired groups using χ(2) analysis.


RESULTS
There were no differences in the incidence of abnormal first- and second-trimester screening tests between the translocation Down syndrome and the complete trisomy 21 groups. History of prior aneuploidy was significantly more frequent in the translocation Down syndrome group, as compared with either complete trisomy 21 fetuses or normal controls.


CONCLUSIONS
Fetuses with translocation Down syndrome present with the same screening abnormalities as fetuses with complete trisomy 21.
Bornstein
Eran
E
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, New York University School of Medicine, Lenox Hill Hospital, New York, NY, USA.
Lenchner
Erez
E
Donnenfeld
Alan
A
Jodicke
Cristiano
C
Keeler
Sean M
SM
Kapp
Sara
S
Divon
Michael Y
MY
D000328:Adult; D000649:Amniocentesis; D000782:Aneuploidy; D016022:Case-Control Studies; D015193:Chorionic Villi Sampling; D002891:Chromosomes, Human, Pair 21; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D014178:Translocation, Genetic