[Results of 1043 prenatal cytogenetic studies: retrospective study in the context of applicability of interphase FISH in prenatal diagnosis]].
OBJECTIVE
The risk of aneuploidy in a fetus is the main reason for referral in approximately 80% of prenatal studies. Recently, a new method for rapid detection of the most frequent aneuploidies affecting chromosomes 13, 18, 21, X and Y has been developed. Fluorescence in situ hybridisation (FISH) on uncultured fetal cells with probes specific for these chromosomes has been described which enables diagnosing aneuploidies within 24 to 48 hours. The purpose of the study was evaluation of clinical utility of this new method in prenatal diagnostics.


METHODS
Retrospective analysis of the results of 1043 prenatal cytogenetic studies performed with conventional banding methods was done. Number and type of chromosomal abnormalities found in different categories of indications with special emphasis on aberrations undetectable by FISH were analysed.


RESULTS
Chromosomal aberrations were found in 4.7% studies. The frequency of aneuploidies was 1.8% accounting for 35.8% of all diagnosed chromosomal abnormalities. In the group of 854 studies performed for elevated risk of aneuploidy it accounted for 60.7% (17/28) abnormalities. All other aberrations could not be detected by FISH with probes for most frequent aneuploidies. Among them, there were 6 unbalanced: del (8) and pseudic (15) with known abnormal phenotype and 4 marker chromosomes with unknown clinical consequences. Three other abnormalities were balanced but familial origin of them was documented.


CONCLUSIONS
A karyotype using classical banding methods should be performed whatever the indication of prenatal study is. It is the only fully informative method able to detect all chromosomal abnormalities. Interphase FISH assay must be considered as a complementary procedure to fetal karyotype analysis as it is designed only for aneuploidy identification. However it may be a very useful method for rapid diagnosis in specific clinical conditions especially in the cases of high risk of aneuploidy.
Bocian
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Zakładu Genetyki Instytutu Matki i Dziecka.
Jakubów-Durska
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K
Mazurczak
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T
D000328:Adult; D002869:Chromosome Aberrations; D003582:Cytogenetics / Q000379:methods; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008403:Mass Screening; D011003:Ploidies; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012189:Retrospective Studies
Retrospektywna analiza 1043 wyników prenatalnych badań cytogenetycznych w kontekście przydatności diagnostycznej FISH interfazowej.