Recent Assembly of an Imprinted Domain from Non-Imprinted Components
Figure 1
Genes of the PWS-AS Imprinted Domain
(A) The PWS-AS imprinted domain in human and mouse. Paternal or maternal expression is indicated by arrows. The yellow region of SNURF/SNRPN represents the ICR. UBE3A-AS is an antisense transcript that includes arrays of untranslated snoRNA genes.
(B) Comparison of the eutherian SNRPN–UBE3A region with its ancestral arrangement in non-eutherian vertebrates. Pink represents genes that are co-linear in humans through to fish, purple represents human Chromosome 2 genes that are adjacent to the PWS-AS homologous region in the ancestral arrangement, orange represents eutherian-specific genes or elements, and brown the unlinked gene SNRPB′ that duplicated to form SNRPN. In marsupials, monotremes, chicken, and fish, UBE3A lies close to a human Chromosome 2 gene CNGA3, and there are no snoRNAs. In zebrafish, chicken, and platypus, only SNRPB′ is present, but in marsupials tandem duplication gave rise to SNRPN, which was relocated next to UBE3A in eutherians.