دانلود Non‐invasive prenatal screening for chromosomal abnormalities using circulating cell-free fetal DNA in maternal plasma: Current applications, limitations and prospects

Abstract

Background: Prenatal screening for chromosomal aneuploidies was initiated in the 1970s, based in maternal age. With the introduction of serum and ultrasound biomarkers, new screening methodologies, with higher detection rates and lower false-positive rates, were implemented. More recently, cell-free fetal DNA testing was presented as a non-invasive test that uses maternal plasma to obtain fetal DNA in order to search for fetal aneuploidies or other chromosomal imbalances. Methodology: Searches of PubMed were performed, being restricted to English-language publications and to humans. The search period was from January 2010 to July 2016. A total of 3416 citations were examined by title and abstract, 159 were analyzed integrally and a backward search of relevant studies led to the analyses of an additional 67 articles. Results: When compared to other prenatal screening methods of common aneuploidies, cell-free fetal DNA testing has the best performance. However, its high cost and failure rate prevent at present time its implementation as a universal prenatal aneuploidy screening. Recent inclusion of microdeletions and microduplications in the panel of chromosomal anomalies to be screened by cell-free fetal DNA testing is a matter of concern, because of the low positive predictive value for these changes, and the associated significant cumulative false-positive rate. Discussion: Cell-free fetal DNA testing represents the best screening method for common aneuploidies, and should its cost decrease, its use may be more widespread. But presently, contingent screening strategies may represent a cost-effective alternative. This review provides a current overview of this relevant theme.