TRISOMY 2: CONFINED PLACENTAL MOSAICISM IN A FETUS WITH INTRAUTERINE GROWTH RETARDATION

In a pregnancy that was monitored due to increased risk for Down syndrome in the triple test, a normal karyotype was found in amniocentesis. Follow‐up by serial ultrasound examinations revealed intrauterine growth retardation (IUGR) at 20 weeks of gestation. The parents decided to terminate the pregnancy and the karyotype of the placental fibroblasts was 47,XX,+2. Analysis of polymorphic markers of chromosome 2 demonstrated (a) that trisomy 2 was confined to the placenta (CPM), (b) that the trisomy 2 cell line was a result of a meiotic I error of paternal origin, and (c) that the fetal tissues with a normal karyotype were biparental disomy 2. © 1997 by John Wiley & Sons, Ltd.