Quantification of fetal nucleated cells in maternal blood of pregnant women with a male trisomy 21 fetus using molecular cytogenetic techniques.
BACKGROUND
Prenatal diagnosis of trisomy 21 is based on fetal karyotyping generally obtained using invasive methods. During pregnancy, the circulating fetal cells in maternal blood constitute a potential source for development of a noninvasive prenatal diagnosis. The objective of this study was the identification and quantification of all fetal nucleated cells per unit volume of peripheral blood of pregnant women carrying male fetuses with trisomy 21 using molecular cytogenetic techniques.


METHODS
Peripheral blood samples were obtained from 16 women carrying male fetuses with trisomy 21. We used a simple and rapid method of harvesting blood without recourse to any enrichment procedures or cell-separation techniques. To evaluate the potential of this method, 16 specimens were analyzed by molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH) and primed in situ labeling (PRINS) using specific probes to chromosomes X, Y and 21.


RESULTS
The number of fetal cells varied between 6 and 32 per mL of maternal blood. This number is 3-5 times higher than that from normal pregnancies.


CONCLUSIONS
Our current results are in agreement with the results previously reported by other groups showing that the number of fetal cells in maternal blood in trisomic 21 pregnancies is higher than in normal pregnancies. This high number of fetal cells is regarded as an advantage for the development of a noninvasive prenatal diagnostic test.
Krabchi
Kada
K
Service of Genetics, Department of Pediatrics, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada.
Gadji
Macoura
M
Samassekou
Oumar
O
Grégoire
Marie-Chantal
MC
Forest
Jean-Claude
JC
Drouin
Régen
R
D000328:Adult; D002891:Chromosomes, Human, Pair 21 / Q000737:chemistry; D041321:Chromosomes, Human, X / Q000737:chemistry; D041322:Chromosomes, Human, Y / Q000737:chemistry; D020732:Cytogenetic Analysis; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D004900:Erythroblasts / Q000737:chemistry*; D005260:Female; D005312:Fetal Blood / Q000166:cytology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis; D020401:Primed In Situ Labeling; D012680:Sensitivity and Specificity