Genetic and epigenetic alterations have been identified that lead to 
transcriptional deregulation in cancers. Genetic mechanisms may affect single 
genes or regions containing several neighboring genes, as has been shown for DNA 
copy number changes. It was recently reported that epigenetic suppression of 
gene expression can also extend to a whole region; this is known as long-range 
epigenetic silencing. Various techniques are available for identifying regional 
genetic alterations, but no large-scale analysis has yet been carried out to 
obtain an overview of regional epigenetic alterations. We carried out an 
exhaustive search for regions susceptible to such mechanisms using a combination 
of transcriptome correlation map analysis and array CGH data for a series of 
bladder carcinomas. We validated one candidate region experimentally, 
demonstrating histone methylation leading to the loss of expression of 
neighboring genes without DNA methylation.