English 
Italian Screening prenatale delle principali anomalie cromosomiche nell’ambito del percorso assistenziale del Piemonte
Prenatal screening of the main chromosomal abnormalities: the experience of the Piemonte region (Italy)
AUTORI
1 Dipartimento di Medicina di Laboratorio, Azienda Ospedaliera Universitaria Città della Salute e della Scienza, Torino,
2 Dipartimento di Ostetricia e Ginecologia (Ospedale Sant’Anna), Azienda Ospedaliera Universitaria Città della Salute e della Scienza, Torino
3 Dipartimento di Scienze Mediche, Università degli Studi di Torino
ABSTRACT
Prenatal screening of the main chromosomal abnormalities: the experience of the Piemonte region (Italy)
Introduction: the purpose of prenatal diagnosis is the identification of the 3% of fetuses with chromosomal abnormalities. Prenatal testing relies on ultrasound measurements and biochemical markers, but in recent years it has been moving towards Non-Invasive Prenatal Testing (NIPT) to determine the fetal risk for genetic disorders. The aim of this study is to provide an assessment of the implementation of cell-free DNA (cfDNA) screening for the three main aneuploidies [Down (T21), Edwards (T18), and Patau (T13) syndromes] using a Contingent approach in the Piedmont region in Italy, where currently Combined, Wald and Integrated tests are offered by the National Health System.
Methods: a prospective NIPT study was carried out among women referred for invasive prenatal diagnosis in Città della Salute e della Scienza in Turin, Italy. The plasma fraction was extracted, stored at −20°C and cfDNA measured using an automated system based on rolling circle replication.
Results: a total of 805 women were recruited including 48 T21, 25 T18, and 3 T13 affected pregnancies. The detection rates (DRs) were 100% (93%-100%), 96% (80%-100%), 67% (9.4%-99%), and the false-positive rates (FPRs) were 0.14% (0.00%-0.79%), 0.78% (0.29%-1.7%), and 0.26% (0.03%-0.95%) for T21, T18, and T13 syndromes, respectevely.
Conclusion: the screening performance of cfDNA is substantially higher than the Combined or Integrated tests. Considering the offering a Contingent cfDNA screening policy, it is relevant to assess the test performance in samples in the “grey zone” conventional screening results (i.e., risk 1 in 100 – 2 500 for T21 syndrome ) compared with the previous one (risk higher than 1 in 100 or lower than 1 in 2500).