Complete discrepancy between abnormal fetal karyotypes predicted by QF-PCR rapid testing and karyotyped cultured cells in a first-trimester CVS.
A chorion villus sample (CVS) biopsied at 11 weeks' gestation for raised nuchal translucency, revealed monosomy X (presumptive 45,X karyotype) by QF-PCR for rapid aneuploidy testing for chromosomes 13, 18, 21, X and Y. Long-term culture gave the karyotype: 47,XY,+ 21[66]/49,XYY,+ 21,+ 21 [22]. This discrepancy prompted redigestion of the combined residual villus fragments from the original QF-PCR assay. The repeat QF-PCR assay identified the presence of trisomy 21 and a Y chromosome consistent with a 47,XY,+ 21 karyotype. A double non-disjunction event early in embryogenesis in a 47,XY,+ 21 conceptus with subsequent cell lineage compartmentalisation of the three observed cell lines (45,X; 47,XY,+ 21 and 49,XYY,+ 21,+ 21) would account for these results. This is the first reported case to describe complete discrepancy at diagnosis between abnormal karyotypes detected by QF-PCR rapid aneuploidy testing and a cultured karyotype in the same CVS.
Waters
Jonathan J
JJ
Cytogenetics Laboratory, NE Thames Regional Genetics Service, Gt Ormond St Hospital, London WC1N 3BG, UK. waterj@gosh.nhs.uk
Walsh
Sally
S
Levett
Lisa J
LJ
Liddle
Stuart
S
Akinfenwa
Yinka
Y
D000328:Adult; D002478:Cells, Cultured; D015193:Chorionic Villi Sampling / Q000379:methods*; D002869:Chromosome Aberrations; D041322:Chromosomes, Human, Y / Q000235:genetics; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D006801:Humans; D007621:Karyotyping / Q000379:methods; D009030:Mosaicism; D048208:Nuchal Translucency Measurement; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy