Confined placental mosaicism revisited: Impact on pregnancy characteristics and outcome

Abstract

ObjectivesWe wanted to re-evaluate the influence of confined placental mosaicism subtypes (type 2 and type 3) on pregnancy characteristics and outcome.Material and methodsFrom July 2009 to December 2015, 5512 chorionic villus samplings were performed in our Fetal Medicine Center. Conventional karyotyping was performed after long-term and short-term cultured villi to define type 2 or type 3 confined placental mosaicisms. Karyotype after amniocentesis was performed to exclude true fetal mosaicism, when appropriate. Pregnancy characteristics and outcomes were collected and compared to a control population.ResultsThirty-six (0.65%) confined placental mosaicisms were observed (13 type 2 and 23 type 3). Nuchal translucency was not increased for type 2 and type 3 confined placental mosaicisms. Pregnancy characteristics and outcomes were comparable between type 2 confined placental mosaicisms and the control population. In type 3 confined placental mosaicisms, median first trimester serum pregnancy-associated plasma protein A was lower than for the control population (p<0.001), preterm births were noticed in 56% (p<0.001), small for gestational age newborns in 74% (p<0.001), and adverse pregnancy outcome was reported in 35% (p<0.01).ConclusionAlthough type 2 confined placental mosaicisms appeared to have no influence on pregnancy characteristics and outcome, type 3 confined placental mosaicisms were associated with low levels of first trimester serum pregnancy-associated plasma protein A, preterm birth, small for gestational age newborns, and adverse pregnancy outcomes.

Rare autosomal trisomies: comparison of detection through cell‐free DNA analysis and direct chromosome preparation of chorionic villus samples

“…Most, but not all, of these abnormalities were CPM. The significance of CPM with trisomy 16 is now recognized [32][33][34][35] , but the consequences of other RATs remain controversial [36][37][38][39][40][41][42] . The need to understand the clinical implications of RATs in cytotrophoblasts has become urgent because of the introduction of genome-wide cfDNA testing that also detects these abnormalities.…”

Single-cell analysis of human embryos reveals diverse patterns of aneuploidy and mosaicism

“…Long-standing questions in the field of preimplantation genetics include how aneuploid cells are distributed among different cell types and how this changes throughout development. Cell type-specific propensities and/or tolerances for aneuploidy could help explain observations such as confined placental mosaicism observed at later developmental stages (Toutain et al 2018) . Meanwhile, selection against aneuploid cells within mosaic embryos could help explain recent reports that some embryos that test mosaic with PGT-A can result in healthy live births after intrauterine transfer (Greco et al 2015) .…”

Interest of chromosomal microarray analysis in the prenatal diagnosis of fetal intrauterine growth restriction

“…Indeed, there was heterogeneity in the diagnostic criteria of IUGR, using different thresholds of percentile and different reference curves; heterogeneity in the design of experiments (CMA performed directly or after FISH or quantitative polymerase chain reaction [qPCR], with different array platforms designs, different samples) and some reported cohorts were of small size. In 2016, Borrell's study reported prenatal CMA exclusively performed on amniotic fluid (unable to identify confined placental mosaicism, which is an important cause of IUGR) with microarrays carrying bacterial artificial chromosome (BAC) probes, providing lower resolution. Some CNVs were not interpreted and “labeled”; indeed, some CNV seemed to be a VOUS rather than real pathogenic CNV (according to published criteria).…”