title: Genomic loss of imprinting in first-trimester human placenta.
abstract: OBJECTIVE
  The purpose of this study was to investigate imprinting patterns in first-trimester human placentas.
  
  
  METHODS
  Using samples of 17 first-trimester and 14 term placentas from uncomplicated pregnancies, we assessed loss of imprinting (LOI) at the RNA level in a panel of 14 genes that are known to be imprinted in the placenta with the use of a quantitative allele-specific reverse transcriptase polymerase chain reaction analysis of those genes that contained readout single nucleotide polymorphisms in their transcripts.
  
  
  RESULTS
  There is significant LOI (ie, biallelic expression) in all 14 genes in first-trimester placentas. LOI was more variable and generally at lower levels at term. Although there is little difference in gene expression, the level of LOI is higher in the first-trimester placentas, compared with term placentas.
  
  
  CONCLUSIONS
  Genomic imprinting appears to be a dynamic maturational process across gestation in human placenta. In contrast with prevailing theories, epigenetic imprints may continue to evolve past 12 weeks of gestation.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Science, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Yevgeniya
authors.initials: Y
authors.lastname: Pozharny
authors.forename: Luca
authors.initials: L
authors.lastname: Lambertini
authors.forename: Yula
authors.initials: Y
authors.lastname: Ma
authors.forename: Lauren
authors.initials: L
authors.lastname: Ferrara
authors.forename: Christian G
authors.initials: CG
authors.lastname: Litton
authors.forename: Andreas
authors.initials: A
authors.lastname: Diplas
authors.forename: Adam R
authors.initials: AR
authors.lastname: Jacobs
authors.forename: Jia
authors.initials: J
authors.lastname: Chen
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Stone
authors.forename: James
authors.initials: J
authors.lastname: Wetmur
authors.forename: Men-Jean
authors.initials: MJ
authors.lastname: Lee
mesh_terms: D044127:Epigenesis, Genetic / Q000235:genetics; D005260:Female; D018392:Genomic Imprinting; D023281:Genomics; D006801:Humans; D010920:Placenta / Q000502:physiology*; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction