The detailed entries of the Imprinted Gene Catalogue database were created by Benjamin Tycko, Columbia University, New York and are updated by Ian Morison


Detailed entry for Gene:

MBII genes
HBII genes


Human Chr15q11-q13
Mouse Chr7 (central)




The maternal allele of the Pwcr1/MbII locus is silent; paternal allele active in mice and humans (Cavaille J et al, 2000; de los Santos T et al, 2000; Meguro M et al, 2001).
These snoRNAs (HBII-13, HBII-85, HBII-52, HBII-436, HBII-437, HBII438A, HBII438B) are hosted by the paternally expressed, extended 148 exon SNURF-SNRPN transcript (Runte M et al, 2001).

Gene Product:

This locus consists of multiple tandemly repeated intronless genes, with a core sequence encoding a small nucleolar RNA (snoRNA) containing a C/D box motif (Cavaille J et al, 2000; de los Santos T et al, 2000; Meguro M et al, 2001)). Many of the genes in this locus are expressed exclusively or predominantly in brain (Cavaille J et al, 2000).

Functional Data:

In general, snoRNAs function within nucleoli as guidance RNAs in the post-transcriptional 2'-O-ribose-methylation of ribosomal RNA and other small nuclear RNAs. However, the brain-specific C/D box snoRNA HBII-52 has an 18-nt conserved complementarity to a segment of serotonin 2C receptor mRNA, leading to speculation that it may affect the processing of this mRNA (Cavaille J et al, 2000). Paternal deletions of this region (Snrpn-Pwcr1-Ube3a) in mice show failure to thrive and lethality in the early post-natal period (Tsai TF et al, 1999). Since Snrpn and Ube3a deletions are individually not lethal, deficiency of Pwcr1 may account for the lethality (Cavaille J et al, 2000). PWCR1/HB11, which lies within the Prader-Willi syndrome (PWS) deleted region, is therefore considered a candidate gene for directly contributing the certain features of the PWS phenotype.


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