Genomic loss of imprinting in first-trimester human placenta.
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.
Pozharny
Yevgeniya
Y
Department of Obstetrics, Gynecology, and Reproductive Science, Mount Sinai School of Medicine, New York, NY, USA.
Lambertini
Luca
L
Ma
Yula
Y
Ferrara
Lauren
L
Litton
Christian G
CG
Diplas
Andreas
A
Jacobs
Adam R
AR
Chen
Jia
J
Stone
Joanne L
JL
Wetmur
James
J
Lee
Men-Jean
MJ
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