An imprinted mouse transcript homologous to the human imprinted in Prader-Willi syndrome (IPW) gene

The Prader-Willi syndrome (PWS) is caused by genomic alterations that inactivate imprinted, paternally expressed genes in human chromosome region 15q11-q13. IPW, a paternally expressed gene cloned from this region, is not expressed in individuals with PWS, and is thus a candidate for involvement in this disorder. The IPW transcript does not appear to encode a polypeptide, suggesting that it functions at the level of an RNA. We have now cloned a mouse gene, named Ipw, that has sequence similarity to a part of IPW and is located in the conserved homologous region of mouse chromosome 7. The Ipw cDNA also contains no long open reading frame, is alternatively spliced and contains multiple copies of a 147 bp repeat, arranged in a head-to-tail orientation, that are interrupted by the insertion of an intracisternal A particle sequence. Ipw is expressed predominantly in brain. In an interspecies (M.musculus x M.m.castaneus) F1 hybrid animal, expression of Ipw is limited to the paternal allele. We propose that Ipw is the murine homolog of IPW.