This retrospective study of placental mosaicism in CVS is the largest single centre study to date and provides a figure for the occurrence of completely discrepant results between QF-PCR and karyotype due to placental mosaicism. This study also demonstrates that the presence of triallelic peaks at QF-PCR is not sufficient to exclude the presence of placental mosaicism.

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Constitutional telomeric translocations are rare chromosome rearrangements. They are thought to occur as a result of chromosome breakage and subsequent ligation with the telomeric sequence of a different chromosome. Most frequently they occur as de novo events and, depending on the donor chromosome breakpoint, may be associated with an abnormal phenotype. We report a case of an unbalanced translocation involving the long arm of chromosome 15 and the short arm of chromosome 8 [45,XY, der(8)t(8;15)(p23.3;q11.2),-15], diagnosed prenatally; the father carried an unbalanced translocation of the long arm of chromosome 15 and the short arm of chromosome 2 [45,XY,der(2)t(2;15)(p25.3;q11.2),-15]. Both translocations were shown to have telomere repeat sequences at the translocation breakpoints. There was no apparent imbalance of euchromatic material in either translocation, and no associated abnormal phenotype.

Glass bead disruption of chorionic villus samples is an effective, inexpensive and rapid DNA extraction method that dissociates villus ensuring that DNA from both cytotrophoblast and mesenchyme cells is represented in the supernatant. Extracted DNA produced is suitable for CVS-PCR and can be stored stably at - 20 degrees C.

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