C15orf2 and a novel noncoding transcript from the Prader-Willi/Angelman syndrome region show monoallelic expression...

The Prader-Willi syndrome (PWS) region contains several genes transcribed from the paternal chromosome only. We have previously identified a testis-specific gene, C15orf2, which maps between NDN and SNURF-SNRPN and is expressed from both alleles. Here we report on two novel genes (prader-willi region non-protein-coding RNA 1 and 2) located between NDN and C15orf2. By database search we found five partially duplicated copies, of which only one of each appears to be active. PWRN2 is expressed only in testis and is biallelic. PWRN1 is biallelically expressed in testis and kidney, but monoallelically in fetal brain. Methylation analysis of a CpG island 15 kb upstream of exon 1 showed absence of methylation in spermatozoa, but methylated and unmethylated alleles in fetal brain. Reinvestigation of C15orf2 revealed that this gene is also expressed in fetal brain and that expression in this tissue is monoallelic. We conclude that PWRN1 and C15orf2 may play a role in PWS.