Methylation status of / is stable across populations, monozygotic twin pairs and in majority of tissues.

The aim of this study was to characterize the methylation level of a polymorphically imprinted gene, /, in human populations and somatic tissues.48 datasets, consisting of more than 30 tissues and >30,000 individuals, were used. methylation status is associated with twin status and ethnic background, but the variation between populations is limited. Monozygotic twin pairs present concordant methylation, whereas ∼30% of dizygotic twin pairs present discordant methylation in the locus. The methylation levels of are uniform across somatic tissues, except in cerebellum and skeletal muscle. The imprint may be established in the oocyte, and, after implantation, the methylation status is stable, excluding a few specific tissues.