Prenatal diagnostics of chromosomal aberrations in the Czech Republic: Actual data and important trends

The main goal of this study was to analyse the spectrum of chromosomal aberrations that were diagnosed during prenatal diagnostics in the Czech Republic in 2016. We present a retrospective epidemiological analysis that is based on the official data from the National Registry of Congenital Anomalies that is run by the Institute of Health Information and Statistics of the Czech Republic. Additional data were obtained actively from the departments of medical genetics and prenatal diagnostics under the guidance of the Czech Society of Medical Genetics and Genomics. In 2016 there were 577 cases of chromosomal aberrations identified during prenatal diagnostics in the Czech Republic. The most important group of aberrations were the three main autosomal trisomies - Down, Edwards and Patau syndromes which were identified in 64.8 % of cases. The most frequent of them was the Down syndrome, that was identified in 271 cases (47 % of all cases identified in 2016). Other aberrations (including the abnormalities of the gonosomes and other autosomal anomalies) were still identified in more than one third of cases, although the screening programs do not primarily focus on them. Combined screening in the first trimester and following prenatal diagnostics mostly identify main autosomal trisomies. Screening is currently the most important clinical referral for the invasive prenatal diagnostics procedures. We also observe important time trend of decreasing numbers of invasive diagnostics procedures - while the overall prenatal detection rate of chromosomal aberrations is not negatively affected. Keywords: hromosomal aberrations, prenatal diagnostics, prenatal screening.