Parentally imprinted genes regulate hematopoiesis—new evidence from the Dlk1–Gtl2 locus

Genomic imprinting is an epigenetic process that leads to the expression of a small set of genes in a parental origin-specific manner so that they are expressed either from the maternal or the paternal set of chromosomes (1). So far, only ~100 genes have been identified as parentally imprinted, and it is well known that they play crucial roles in embryogenesis, fetal growth, the totipotent state of the zygote, and the pluripotency of developmentally early stem cells (1-3). Genomic imprinting is also the most important mechanism preventing parthenogenesis (4,5). Deregulation of the expression of imprinted genes during embryogenesis also leads to developmental disorders such as Beckwith-Wiedemann syndrome, Angelman syndrome, and Prader-Willi syndrome (1).