Mitochondrial Ribosomal Protein L23 (MRPL23)

The closely linked insulin growth factor-2 (IGF2) and H19 genes on 11p15.5 are monoallelically expressed as the result of genomic imprinting and show altered expression in Wilms tumors (WT1). L23MRP (for L23 mitochondrial-related protein), which is oriented 'tail-to-tail' with H19 and is transcribed to within 40-kb of the last H19 exon. L23MRP is expressed biallelically in many mid-fetal and adult human tissues. The gene is also expressed at normal levels in Wilms tumors, which have lost expression of H19 either via loss of the maternal chromosome 11p15.5 or via an epigenetic pathway involving site-specific DNA hypermethylation. These data indicated that, at least in postembryonic stages, L23MRP is functionally insulated from the IGF2/H19 imprinted domain.