Karyotypic differences between cells from placenta and other fetal tissues

Abstract

Six cases are reported with discrepancies between the karyotypes of placental cells and cells from other fetal tissue. The respective findings were: 48, + 7, + 18 resp. 47, + 18. 46,i(18q) resp. 46,del18(p11). 46,XX resp. 46,XX/47,XXX. 46,X,Yq+ and 46,XY resp. 46,XY. 46/47, + 12 resp. 46. 46/47, + 5 resp. 46. These differences were found in both early and term pregnancies. Care should be taken in deducing the fetal karyotype from the chromosomal pattern of placental cells.

Discrepancies in cytogenetic results between different tissues in two fetuses with Wolf- Hirschhorn syndrome

“…Structural chromosome aberrations often have a much more complex mechanism of formation than the end product would suggest, and secondary rearrangements of a given aberration in the zygote are more frequent than expected. Cytogenetic discrepancies between the chorionic villus and amniocytes or fetal tissues (e.g., blood, fibroblasts) occur at a frequency of about 1 % to 2 % (Verjaal et al, 1987;Ledbetter et al, 1992;Pittalis et al, 1994;Wolstenholme, 1994;Farra et al, 2000). In most such cases, however, numerical aberrations are present only in one tissue (usually the chorion).…”

“…Examples include an 11q+ karyotype in the chorion, coupled with a finding of 11q-in the fetus (Porter et al, 1999), and an i(18q) at CVS with a del(18p) in the fetus (Verjaal et al, 1987).…”

The shiverer mouse mutation shi/shi: rescue and preimplantation detection

“…Another important reason for having additional biopsy material is that many genetic diseases, such as cystic fibrosis (Roberts, 1990), show extensive heterogeneity and additional testing may be necessary. However, some reports indicate that karyotypic differences exist between the placenta and other fetal tissue (Verjaal et al, 1987). We will be able to test this in future experiments which allow a number of biopsied embryos to go to term.…”

Placental mosaicism in a case of 46,XY, −22, +t(22;22)(p11;q11) or i(22q) diagnosed at amniocentesis

“…Discrepancies between the chromosome constitution of chorionic villi and the fetus proper have been reported to occur in 0.7-3 per cent of samples (Hogge et af., 1985;Simoni et al, 1985;Verjaal et al, 1987;Breed et al, 1990).…”