Abstract
More than 100 human genes are known to be imprinted by epigenetic mechanisms. This status allows the specific expression from only one of the two paternal alleles, corresponding to a functional parent-of-origin specific hemizygosity. This parental imprint undergoes a cycle during the life of an organism that allows an epigenetic reprogramming in each generation. During germ cell formation, all epigenetic marks are erased, and then 1000 CpG islands become de novo methylated in the mature germ cells. After fertilization, a further wave of demethylation takes place and affects nearly all methylated CpGs with the exception of the imprinted genes. Thus, the imprinting marks are transmitted from the parental gametes and are then maintained in the somatic cells of an individual. However, in various tissues and organs the imprinting settings can be modified and is linked to the rapid differentiation and formation of various tissues and organs. Among others, one fundamental molecular process in this imprinting cycle is DNA methylation. It is mainly catalyzed by DNA methyltransferases, and is generally associated with gene silencing.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
