Rapid prenatal diagnosis of Down syndrome using quantitative fluorescence in situ hybridization on interphase nuclei.
OBJECTIVE
Presently, conventional cytogenetic analysis of metaphase chromosomes remains the reference approach in prenatal diagnosis. However, this method is labor-intensive and time-consuming. The first step toward the rapid identification of aneuploidies is achieved by interphase fluorescence in situ hybridization (FISH) with centromeric or locus-specific probes. Spot counting using this type of probes is a reliable approach, but is very time-consuming with some technical and biological limitations. In this study, we present a new FISH method using image cytometry for the detection of trisomy 21 within interphase nuclei.


METHODS
The method is based on a comparative quantitation of the fluorescence signals emitted by whole chromosome 21 and 22 painting probes cohybridized on interphase nuclei. The chromosomal imbalance was determined with an automated image cytometer by detecting an abnormal ratio of both fluorescence emissions when compared with the ratio obtained in normal cells.


RESULTS
Ten blood samples and twenty amniotic fluids were analyzed. Results from FISH and standard cytogenetics were compared and 100% correlation was achieved.


CONCLUSIONS
This method, which enables an easy detection of chromosomal imbalances without a need for metaphase preparations, can be applied to the diagnosis of trisomy 21 and extended to other disorders with chromosomal imbalances. Compared to other interphase FISH techniques, it avoids spot-scoring difficulties.
Truong
Khuong
K
Cytogénétique Moléculaire et Oncologie, UMR147, CNRS-Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. khuong.truong@curie.fr
Gibaud
Anne
A
Dupont
Jean-Michel
JM
Guilly
Marie-Nöelle
MN
Soussaline
Françoise
F
Dutrillaux
Bernard
B
Malfoy
Bernard
B
D000328:Adult; D000649:Amniocentesis; D002467:Cell Nucleus / Q000235:genetics*; D002478:Cells, Cultured; D002891:Chromosomes, Human, Pair 21; D002892:Chromosomes, Human, Pair 22; D020732:Cytogenetic Analysis; D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics*; D005240:Feasibility Studies; D005260:Female; D018628:Gene Dosage; D006801:Humans; D019044:Image Cytometry / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007399:Interphase / Q000235:genetics; D007620:Karyometry; D008423:Maternal Age; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D012680:Sensitivity and Specificity