Abstract: Epigenetic modification especially DNA methylation plays an important role in controlling the functions of the cells. 70% to 80% of the GpG locus in mammalians are methylated .Hypermethylated DNA associate with the silence of the genes, and hypormethylated DNA can activate genes transcription. Furthermore, DNA methylation status is not as steady as that in genome，and there are series of restructure such as methylation pattern erasure,methylation pattern re-establishment and methylation pattern maintenance occurring in primordial germ cells（PGCs）and the early embryo. Assisted reproductive technology （ART） accounts for 1 to 3% of annual births in industrialized countries and continues to increase rapidly. Due to the variability in ART protocols and the rarity of imprinting disorders，it is difficult to clarify the causative relationship between ART and an increased incidence of imprinting disorders. Except for an increased incidence of premature births, it has been confirmed that the procedure of ART may result in abnormal epigenetic modification and reorganization for both germ cells and embryos. Beckwith-Wiedemann syndrome (BWS), Prader-Willi syndrome (PWS) and so on are the most representative imprinting disorders. Recently published articles about DNA methylation and the changes of DNA methylation during embryonic development as well as the relationships between the DNA methylation and the assisted reproductive technology (ART) were reviewed in this paper.

Key words: DNA Methylation, Embryonic Development, Reproductive Techniques;Assisted