Inherent Mosaicism and Extensive Mutation of Human Placentas

(Abstracted from Nature 2021;592:80–85) Approximately 1% to 2% of pregnancies involve chromosomal aberrations confined to the placenta. During the first few days of embryogenesis when fetal and placental lineages diverge, clonal expansion and mosaicism may occur, representing a potential pathological divergence from normal clonal dynamics of early embryogenesis.