FISH analysis of fetal nucleated red blood cells from CVS washings in cases of aneuploidy.
OBJECTIVE
In chorionic villus sampling (CVS) the chromosome analysis is inconclusive in 1-2% of the samples. In many cases follow-up amniocentesis is performed. Fetal nucleated red blood cells (FNRBCs) are present in washings of chorionic villus samples. We wanted to establish whether analysis of these true fetal cells, using fluorescence in situ hybridization (FISH), could support the CVS karyotype.


METHODS
We analysed washings of first trimester chorionic villi from non-mosaic 45,X (n=6) and full trisomy 18 cases (n=7). FNRBCs were identified by immunostaining and FISH was performed with chromosome-specific probes for X, Y and 18.


RESULTS
In all 13 samples FNRBCs were present (between 4 and 30 cells per sample). Five cases of monosomy X showed one X signal in 89-100% of the nuclei; in the other case 50% of the nuclei displayed one signal. In the trisomy 18 cases three spots were seen in 60-100% of the cells.


CONCLUSIONS
The CVS aneuploidy was confirmed in FNRBCs in all samples, so FISH on FNRBCs can be used in cases of non-mosaic numerical chromosomal abnormalities. This test can confirm a CVS diagnosis of monosomy X or trisomy 18 and thus minimize the risk for false-positive diagnoses. An additional invasive test may be prevented.
Schuring-Blom
G H
GH
Department of Clinical Genetics, Academic Medical Center, Amsterdam, The Netherlands. G.H.Schuring@amc.uva.nl
Hoovers
J M
JM
van Lith
J M
JM
Knegt
A C
AC
Leschot
N J
NJ
D000782:Aneuploidy; D002467:Cell Nucleus / Q000648:ultrastructure*; D015193:Chorionic Villi Sampling; D002887:Chromosomes, Human, Pair 18; D004912:Erythrocytes / Q000648:ultrastructure*; D005260:Female; D005312:Fetal Blood / Q000166:cytology*; D005865:Gestational Age; D006446:Hemoglobin E / Q000032:analysis; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009006:Monosomy; D011247:Pregnancy; D014314:Trisomy; D014960:X Chromosome; D014998:Y Chromosome
D006446:Hemoglobin E