Abstract
BackgroundNon-invasive prenatal testing (NIPT) is a rapidly developing and widely used method in the prenatal screening. Recently, the widespread use of the NIPT caused a neglecting of the limitations of this technology.Case presentationThe 38-year-old woman underwent amniocentesis because of a high risk of trisomy 2 revealed by the genome-wide Non-Invasive Prenatal Test (NIPT). The invasive prenatal diagnosis revealed the mosaicism for a small supernumerary marker chromosome sSMC derived from chromosome 2. Interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes revealed three signals of centromere 2 in 30% of the cells. GTG-banded metaphases revealed abnormal karyotype (47,XX,+mar[21]/46,XX[19]) and was confirmed by array comparative genomic hybridization (aCGH). Cytogenetic analyses (FISH, aCGH, karyotype) on fetal skin biopsies were performed and confirmed the genomic gain of the centromeric region of chromosome 2. In the placenta, three cell lines were detected: a normal cell line, a cell line with trisomy 2 and a third one with only the sSMC.ConclusionWhole-genome Non-Invasive Prenatal Testing allows not only the identification of common fetal trisomies but also diagnosis of rare chromosomal abnormalities. Especially in such cases, it is extremely important to perform not only NIPT verification on a sample of material other than trophoblast, but also to apply appropriate research methods. Such conduct allows detailed analysis of the detected aberration, thus appropriate clinical validity.
Highlights
Non-invasive prenatal testing (NIPT) is a rapidly developing and widely used method in the prenatal screening
Discordant results between the NIPT and the fetal karyotype have been reported. This can be due to the fact that the fetal cell-free DNA in the maternal blood is derived from the cytotrophoblastic cells of the placenta [9] and confined placental mosaicism (CPM) can yield a discrepancy between NIPT and amniotic fluid analysis
The indication for the prenatal examination in this case was a high risk of trisomy 2 revealed by NIPT test while in invasive diagnostic mosaicism of a small supernumerary marker chromosome derived from chromosome 2 has been detected
Summary
Non-invasive prenatal testing (NIPT) is a rapidly developing and widely used method in the prenatal screening. Case presentation: The 38-year-old woman underwent amniocentesis because of a high risk of trisomy 2 revealed by the genome-wide Non-Invasive Prenatal Test (NIPT). Cytogenetic analyses (FISH, aCGH, karyotype) on fetal skin biopsies were performed and confirmed the genomic gain of the centromeric region of chromosome 2. Non-invasive prenatal testing (NIPT) is a rapidly developing and widely used method in the world. Discordant results between the NIPT and the fetal karyotype have been reported This can be due to the fact that the fetal cell-free DNA (cfDNA) in the maternal blood is derived from the cytotrophoblastic cells of the placenta [9] and confined placental mosaicism (CPM) can yield a discrepancy between NIPT and amniotic fluid analysis. Twin pregnancies, vanisching twing, maternal copy number variations (CNV), maternal mosaicism, as well as maternal malignancies and low-level imbalance-mosaicism examined chromosomes are the most commonly reported reasons for discordance [11,12,13,14,15,16,17,18,19]
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