RING CHROMOSOME-18 IN A FETUS WITH ONLY FACIAL ANOMALIES

We report on a prenatally detected case of ring chromosome 18 [46,XX,r (18)] in amniotic fluid cells of a fetus with an abnormal facial profi le on ultrasound as the only malformation. The chromosome 18 origin of the ring chromosome, of a supernumerary marker chromosome in some cel ls, and of micronuclei was demonstrated by fluorescent in situ hybridi zation with a whole chromosome 18 paint (Cambio) and 18 centromere pro be L1.84. DNA investigations showed deletions of 18p as well as 18q ma terial of r(18), which turned out to be of paternal origin. Autopsy of the fetus after termination of pregnancy at 20 weeks of gestation sho wed no additional malformations, in agreement with the previous ultras ound findings. (C) 1996 Wiley-Liss, Inc.