Homo sapiens C/D box snoRNA HBII-85-25: this snoRNA was first characterized by Cavaillé et al. (2000), de los Santos et al. (2000) and Meguro et al. (2001). It is highly expressed in the brain and uterus, and to a lesser extent in kidney, heart and lung (Cavaille et al., 2002). Due to cross-hybridisation in Northern blot analysis, it could not be assessed if all predicted snoRNAs in this cluster are indeed expressed. As HBII-52 and HBII-13, HBI-85 was not expressed in the brain of a patient with a paternal 15q11-q13 deletion (Prader-Willi syndrome), but was normally expressed when the deletion was maternally inherited (Angelman syndrome). Genomic sequencing revealed that 27 closely related copies HBII-85 are encoded in introns of the large (460kb), paternally expressed, transcription unit (SNURF-SNRNP-UBE3A AS), that is antisense to the maternally expressed UBE3A gene (Runte et al., 2001). The same transcription unit hosts HBII-13, HBII-436, HBII-437 and HBII-438A/B, and 47 copies of HBII-52). The snoRNAs of this cluster are not predicted to guide to 2'O-methylation of a rRNA or snRNA.