EST based method to identify differentially expressed gene clusters along chromosmes

The positional clustering of co-expressed genes is common in prokaryotes (operons) and was recently described in several eukaryote organisms [1-4]. Clusters of highly expressed genes were recently revealed in the Human genome [5] and complementary study [6] suggested that such clusters might mostly consist of housekeeping genes and not of genes with similar tissue expression profiles. In order to specifically analyze tissue specific expression, other studies [7-9] were based on sets of genes expressed in a given tissue. They suggest that clusters of tissue specific genes do exist, and might be more frequent than initially thought.