Intérêt de la biologie moléculaire dans le diagnostic rapide de la trisomie 21 et des aneuploïdies les plus fréquentes

Abstract: Objective: Trisomy of chromosome 13, 18, 21 and sex chromosome aneuploidies are the most common chromosomal abnormalities encountered in prenatal screening and are responsible for polymaformative syndrome associated with severe mental retardation. This high degree of morbidity justifies the prenatal diagnosis of these aneuploidies. Fetal nuchal translucency measurement and maternal serum biochemical marker assessment are the method of choice used for antenatal screening of aneuploidies. This prenatal screening leads to numerous maternal samplings followed by karyotyping which is cost-effective, time consuming, while results are generally returned between 2 and 3 weeks. Our study describes the research of common aneuploidies by molecular biology. We have used on one hand the MLPA kit (MRC Holland) based on amplification of specific DNA probes that hybridize with chromosomes 13, 18, 21, X, Y. On the other hand we have developped multiplex fluorescent PCR, amplifying microsatellite DNA sequences. Patients and methods: We have evaluated the efficiency of these two techniques to detect chromosomal abnormalities by screening 400amniotic fluids or chorionic villi samples obtained from pregnant women presenting a high risk of chromosomal aneuploidy. Results: We have found four trisomies 21, one trisomy 13, one monosomy 13, one trisomy 18, two triploidies, one trisomy X and one Klinefelter syndrome. Discussion and conclusion: In our study we have detected by molecular biology, in less than 48h, 100% of common chromosomal aneuploidies without false positive or false negative results which could lead molecular biology as a method of choice for the rapid detection of common aneuploidies in addition to fetal karyotyping. [Copyright &y& Elsevier]