UNIPARENTAL DISOMY WITH AND WITHOUT CONFINED PLACENTAL MOSAICISM - A MODEL FOR TRISOMIC ZYGOTE RESCUE

In the population of children born after prenatal cytogenetic investig ation in chorionic villi at our department from 1992 to 1995 (N = 3940 ), three are known to us with uniparental disomy. One case of maternal heterodisomy 16 was prenatally discovered because of trisomy 16 in di rect chorionic villi with subsequently normal amniotic fluid cells. Th e other two had normal karyotypes in chorionic villi. Maternal heterod isomy 15 was postnatally detected in one of them because of Prader-Wil li syndrome. Maternal hetero/isodisomy 16 was accidentally encountered in the other case in the course of prenatal DNA analysis of the tuber ous sclerosis complex 2 region at 16p13.3. A model is presented for th e understanding of the various combinations of karyotypes in direct ch orionic villi, cultured chorionic villi and the fetus in the case of s uccessful and unsuccessful trisomic zygote rescue. (C) 1998 John Wiley & Sons, Ltd.