[Methylation of DNA is an epigenetic modification critical for gametic imprinting]

Differences in epigenetic patterns in male and female organisms highlight the key role of epigenetic mechanisms in development, initiated in gametogenesis. A consequence of imprinting is the expression of only one allele--maternal or paternal. Disturbances in imprinting cause genetic disorders (e.g., Angelman syndrome, Prader-Willi syndrome, Beckwith-Wiedemann syndrome, Silver-Russell syndrome) or influence cancer development. Also immature gametes used in artificial reproductive technologies may increase the risk of genetic disorders in offspring. Imprinting is heritable and does not change during the lifetime of an organism.