RESUMO
OBJECTIVE: To investigate DNA methylation and expression of imprinted genes and an imprinted gene network (IGN) in neonates conceived via assisted reproductive technology (ART). DESIGN: Case control. SETTING: Research institution. PATIENT(S): Two hundred sixty-four cases of cord blood and/or placental villi from neonates (101 IVF, 81 ICSI, 82 naturally conceived). INTERVENTION(S): Placentas were obtained at birth for biopsy and cord blood extraction. MAIN OUTCOME MEASURE(S): DNA methylation and expression of imprinted genes. RESULT(S): DNA methylation at the PLAGL1 differentially methylated region (DMR) was significantly higher in IVF cord blood (48.0%) compared with controls (46.0%). No differences were found in DNA methylation between conception modes for KvDMR1 and LINE-1 in cord blood and placenta as well as PLAGL1 and PEG10 in placenta villi. PLAGL1 expression was lower in both IVF and ICSI cord blood groups than in controls (relative quantification of 0.65, 0.74, 0.89, respectively). Analyzing the expression of 3 genes in a PLAGL1 regulated IGN revealed different expression between conception modes and a significant correlation to PLAGL1 expression in only one (KCNQ1OT1). CONCLUSION(S): Our results suggest a stability of DNA methylation at imprinted DMRs; however, we show PLAGL1 methylation/expression to be altered after ART. As PLAGL1 expression correlated with only one of the three IGN genes in cord blood, we propose there is a more complex mechanism of regulating the IGN that may involve other genes and epigenetic modifications in this tissue. Further research investigating IGN-implicated genes in various neonatal tissues is warranted to elucidate the full effects ART-induced alterations to PLAGL1 and the IGN may have on fetal growth/development.
