Abstract:
Background. Non-invasive prenatal testing (NIPT) analyses the
cell-free fetal DNA (cffDNA) present in maternal plasma. It is used for
the screening of autosomal trisomies and sex chromosome aneuploidies
(SCAs).
Objectives. Compare the positive predictive value (PPV) of a
high-risk cffDNA test result for SCAs (Monosomy X,
47,XXX,
47,XXY and
47,XYY) and autosomal trisomies
(T21, T18 and T13) with confirmatory diagnostic tests in singleton
pregnancies. Identify the main reason for discordant and inconclusive
results.
Search strategy . PubMed, Web of Science and Scopus from 2017.
Selection criteria . Primary research articles on cffDNA testing
of autosomal trisomies and SCAs in singleton pregnancies.
Data collection and analysis . The methodological
characteristics of the studies and the statistical results of each
aneuploidy were collected. The risk of bias was assessed using the CASP
tool.
Main results. A total of 14 studies were included. Amongst the
autosomal trisomies, T21 had the highest PPVs, whereas T13 showed the
lowest PPVs. As for the SCAs, the lowest PPVs were found with Monosomy
X. Although discordant and inconclusive results were not rigorously
reported, mosaicism was the main cause of false positives and an
insufficient cffDNA fraction was the main reason for inconclusive
results.
Conclusions. CffDNA is a reliable screening tool for the common
autosomal trisomies, and it is also useful for prenatal screening of
SCAs, although the PPVs are lower. A positive NIPT result should be
followed with a confirmatory test.
Funding . The review was carried out with no funding.
Keywords . Cell-free fetal DNA, non-invasive prenatal testing,
aneuploidy,
trisomy.