title: Chromosomal mosaicism in the fetoplacental unit.
abstract: Cytogenetic prenatal diagnosis on chorionic villi (CV) can be complicated by the detection of "chromosomal mosaicism." This is one of the main issues of first-trimester cytogenetic prenatal diagnosis as it can involve different types of chromosomal abnormalities, and the prediction of the fetal involvement is challenging because the detected abnormal mosaic cell line is not necessarily extended to fetal tissues. In addition, because the cell-free fetal DNA that is targeted by the new technologies for fetal aneuploidy risk assessment is mainly derived from the CV cells, the same challenges related to chromosomal mosaicism can be transferred into this new clinical field. This review illustrates the phenomenon of fetoplacental mosaicism, the management of prenatal diagnosis cases complicated by the detection of such a biological phenomenon, and the implications of its presence for the management of high-risk cfDNA testing results for fetal aneuploidies.
authors.affiliation: TOMA Advanced Biomedical Assays S.p.A., Via Francesco Ferrer 25/27, 21052, Busto Arsizio, Varese, Italy. Electronic address: fgrati@tomalab.com.
authors.forename: Francesca Romana
authors.initials: FR
authors.lastname: Grati
authors.affiliation: TOMA Advanced Biomedical Assays S.p.A., Via Francesco Ferrer 25/27, 21052, Busto Arsizio, Varese, Italy. Electronic address: fmalvestiti@tomalab.com.
authors.forename: Francesca
authors.initials: F
authors.lastname: Malvestiti
authors.affiliation: TOMA Advanced Biomedical Assays S.p.A., Via Francesco Ferrer 25/27, 21052, Busto Arsizio, Varese, Italy. Electronic address: lbranca@tomalab1.com.
authors.forename: Lara
authors.initials: L
authors.lastname: Branca
authors.affiliation: TOMA Advanced Biomedical Assays S.p.A., Via Francesco Ferrer 25/27, 21052, Busto Arsizio, Varese, Italy. Electronic address: cagrati@tomalab1.com.
authors.forename: Cristina
authors.initials: C
authors.lastname: Agrati
authors.affiliation: TOMA Advanced Biomedical Assays S.p.A., Via Francesco Ferrer 25/27, 21052, Busto Arsizio, Varese, Italy. Electronic address: fmaggi@tomalab.com.
authors.forename: Federico
authors.initials: F
authors.lastname: Maggi
authors.affiliation: TOMA Advanced Biomedical Assays S.p.A., Via Francesco Ferrer 25/27, 21052, Busto Arsizio, Varese, Italy. Electronic address: gsimoni@tomalab.com.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Simoni
mesh_terms: D000649:Amniocentesis; D015193:Chorionic Villi Sampling; D002869:Chromosome Aberrations; D020732:Cytogenetic Analysis; D005260:Female; D005317:Fetal Growth Retardation / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D009030:Mosaicism; D010920:Placenta; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012729:Sex Chromosome Aberrations; D014314:Trisomy
keywords: amniocentesis; cell-free DNA testing; chorionic villi; confirmatory prenatal diagnosis; fetal aneuploidies; fetoplacental mosaicism