CHROMOSOMAL MOSAICISM OF EXTRAEMBRYONIC C ELLS DETECTED BY PRENATAL-DIAGNOSIS

Data on detection of chromosomal mosaicism in amnionic cells and chori onic villi obtained by prenatal cytogenetic diagnosis are presented. T he frequency of chromosomal mosaicism in preparations of amniotic flui d cell culture was 2.6% (6 out of 226), and that in ''direct'' villus preparations was 1.6% (13 out of 774). The necessity to perform an add itional analysis of other fetal cells or neonatal lymphocytes to speci fy the diagnosis was shown. The analysis of the outcome of pregnancies during which chromosomal mosaicism in the extraembryonic cells was de tected indicates that these women from a high-risk group of at, both g enetically and obstetrically: in only 8 out of 19 cases did pregnancie s end in normal deliveries at term; in three cases, spontaneous aborti ons occurred at 16 - 31 weeks of gestation; in three cases, the pregna ncies were terminated due to fetal chromosomal aberrations in nonmosai c form; the outcome of pregnancy in five cases was preterm delivery of an underweight newborn.