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Khoueiry R.,French Institute of Health and Medical Research | Ibala-Romdhane S.,Service Cytogenetique et Biologie de la Reproduction | Al-Khtib M.,French Institute of Health and Medical Research | Blachere T.,French Institute of Health and Medical Research | And 3 more authors.
Zygote | Year: 2013

Summary To evaluate the integrity of genomic imprinting in embryos that failed to develop normally following intracytoplasmic sperm injection (ICSI), we analysed the methylation profile of H19 and KCNQ1OT1 imprinting control regions, H19DMR and KvDMR1 respectively, in high-grade blastocysts and in embryos that exhibited developmental anomalies. Significant hypomethylation of KvDMR1 was specifically observed in 5/5 atypical blastocysts graded BC, which probably reflected the vulnerability of the imprint in the inner cell mass during the methylation remodelling phase in the early embryo. In addition, KvDMR1 was hypermethylated in 2/5 CC graded atypical blastocysts and in 2/8 embryos that exhibited developmental delay. H19DMR appeared differentially methylated in all groups of embryos. DNA methyltransfersase 1 (DNMT1) expression was similar in most of the tested embryos and could not account for the abnormal methylation patterns of KvDMR1 observed. © Cambridge University Press 2012.


Al-Khtib M.,French Institute of Health and Medical Research | Perret A.,Femme Mre Enfant Hospital | Khoueiry R.,French Institute of Health and Medical Research | Ibala-Romdhane S.,Service Cytogenetique et Biologie de la Reproduction | And 5 more authors.
Fertility and Sterility | Year: 2011

Objective: To evaluate the integrity of genomic imprinting in oocytes vitrified at the germinal vesicle (GV) stage and in vitro matured (IVM) after thawing. Design: Clinical research and application. Setting: University-based fertility center. Patient(s): Immature oocytes were donated for research by patients who were included in an intracytoplasmic sperm injection program. Intervention(s): Immature oocyte retrieval after ovarian stimulation, followed by oocyte vitrification, thawing, and IVM. Main Outcome Measure(s): Methylation profile of H19 and KCNQ1OT1 imprinting control regions, H19DMR and KvDMR1, respectively. Result(s): Among 184 vitrified GV oocytes, 102 survived thawing (55.4%), 77 (75.5%) of which reached the meiosis II (MII) stage after IVM. One hundred twenty control GV oocytes were only subjected to IVM; 70.8% reached the MII stage. GV vitrified as well as control oocytes acquired full imprint at KvDMR1 after IVM and generally retained the unmethylated state of H19DMR. Conclusion(s): For the first time, we show that oocyte vitrification does not affect the methylation profile of H19DMR and KvDMR1: during their IVM, vitrified GV oocytes acquire DNA methylation in the maternally imprinted KCNQ1OT1 gene with the same efficiency as fresh GV oocytes; the vitrification process does not alter the unmethylated state of the paternally imprinted H19 gene. © 2011 by American Society for Reproductive Medicine.

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