title: Chromosomal Mosaicism in Human Feto-Placental Development: Implications for Prenatal Diagnosis.
abstract: Chromosomal mosaicism is one of the primary interpretative issues in prenatal diagnosis. In this review, the mechanisms underlying feto-placental chromosomal mosaicism are presented. Based on the substantial retrospective diagnostic experience with chorionic villi samples (CVS) of a prenatal diagnosis laboratory the following items are discussed: (i) The frequency of the different types of mosaicism (confined placental, CPM, and true fetal mosaicisms, TFM); (ii) The risk of fetal confirmation after the detection of a mosaic in CVS stratified by chromosome abnormality and placental tissue involvement; (iii) The frequency of uniparental disomy for imprinted chromosomes associated with CPM; (iv) The incidence of false-positive and false-negative results in CVS samples analyzed by only (semi-)direct preparation or long term culture; and (v) The implications of the presence of a feto-placental mosaicism for microarray analysis of CVS and non-invasive prenatal screening (NIPS).
authors.affiliation: Research & Development, Cytogenetics, Molecular Cytogenetics and Molecular Biology, TOMA Advanced Biomedical Assays S.P.A., 25/27 Francesco Ferrer Str., Busto Arsizio 21052, Varese, Italy. fgrati@tomalab.com.
authors.forename: Francesca Romana
authors.initials: FR
authors.lastname: Grati
keywords: amniocentesis; chorionic villi; chromosome mosaicism; confined placental mosaicism; cytotrophoblast; mesenchyme; non-invasive prenatal screening; true fetal mosaicism; uniparental disomy