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Your Environment. Your Health.

DNA Methylation Maps of Early Embryo Development

Alexander Meissner, Ph.D.
Broad Institute of MIT and Harvard
NIEHS Grant U01ES017155

Researchers funded in part by NIEHS used high-throughput sequencing to produce genome-scale maps of DNA methylation at several developmental stages of early embryo development and during derivation of embryonic stem cell lines. This work is one step toward understanding the role of embryonic methylation patterns in normal development and disease.

Epigenetic modifications, including DNA methylation, affect gene expression without changing the genetic code. DNA methylation is drastically reprogrammed during early embryonic development in mice, but this reprogramming has not been well studied in humans. The new DNA methylation maps confirm that global DNA methylation patterns in human embryos closely resemble that of mice.

The researchers showed that there is considerable loss of DNA methylation across most of the human genome just after fertilization and that DNA methylation rapidly increases after implantation. One species difference the researchers identified was that maternally contributed methylation in human eggs is targeted to species-specific sets of CpG island promoters that extend beyond DNA regions known to control genes that are preferentially expressed from one parental chromosome.

Citation: Smith ZD, Chan MM, Humm KC, Karnik R, Mekhoubad S, Regev A, Eggan K, Meissner A. DNA methylation dynamics of the human preimplantation embryo. Nature 511(7511):611-615.