A simple technique for obtaining high quality chromosome preparations from chorionic villus samples using FdU synchronization

Abstract

A fluorordeoxyuridine (FdU) synchronization technique was applied to 30 chorionic villus samples (CVS) from patients undergoing first trimester fetal diagnosis. The villi were incubated for 15 h in the presence of FdU. The block in DNA synthesis was subsequently released using thymidine and after an additional 5 h of incubation the mitotic cells were arrested in metaphases using a high concentration of colcemid. This method results in improved morphology of the chromosomes and a high mitotic index. A diagnostic chromosome analysis could be obtained in each clinical case using at least 15 well-spread metaphases. G-banded karyotypes were prepared of four metaphases in each case. The diagnostic procedure was completed within 48 h from the time of CVS. Use of this technique significantly improves the success rate of 'direct' chromosome analyses from CVS in a busy cytogenetic laboratory.

Cytogenetic confirmation of a positive NIPT result: evidence-based choice between chorionic villus sampling and amniocentesis depending on chromosome aberration

“…The cytotrophoblast originates from the trophoblast of the embryo and traditionally is studied in direct or short-term-cultured villi (STC-villi) [15] and nowadays is tested with NIPT [10]. In contrast, the mesenchymal core of CV, which conventionally is studied in long-term-cultured villi (LTC-villi) [16], better reflects the fetal karyotype.…”

“…For the other trisomies that often are found in CV cytotrophoblast (3,7,8,9,15,16,20,22), the numbers in the ACC CVS database are very small and only individual case reports are published. Therefore, no reliable risk figure as for trisomy 13, 18, or 21 can be drawn from the database or literature.…”

“…For trisomies that are mostly involved in CPM type 3, an amniocentesis will always be the confirmatory procedure of choice. These confirmatory studies not only need to include chromosomal investigations, but also molecular testing for uniparental disomy if an imprinted chromosome (6,7,11,14,15,20) is involved. Moreover, cytogenetic studies should include the investigation of both uncultured as well as cultured cells, the latter for detection of an exceptional case of tissue specific mosaicism that may be missed in uncultured cells, as was shown before [31].…”

“…However, in such cases it is important to realize that although fetal ultrasound abnormalities are to be expected in case of a fetal trisomy, their absence does not exclude that the fetus is affected with trisomy mosaicism. Moreover, if an imprinted chromosome (6,7,11,14,15,20) is involved, there is a risk for uniparental disomy, which causes disease that may not be detectable with ultrasound investigations and which may be a reason for invasive testing [41].…”

Microtechnologies Enable Cytogenetics

“…In recent years, there has been considerable interest in fathoming the underlying process of chromosome spreading (Chattopadhyay et al, 1992;Gibas et al, 1987;Sasai et al, 1996). These explorations have also resulted in a number of devices aimed at automating the chromosome spreading protocol (Henegariu et al, 2001;Qu et al 2008;Yamada et al, 2008).…”