Our analysis of differential gene expression in 11q-deleted tumors vs. MNA neuroblastomas pinpointed some candidate tumor suppressor/DNA repair genes within the region of 11q that is deleted, such as ATM, MLL, H2AFX, and CHK1. Recently, the importance of aberrant gene expression within this region was underscored by the finding that decreased expression of genes within the region of interest at 11q was observed only in those 11q-deleted tumors with an aggressive clinical phenotype [28]. This evidence concerns the gene ATM and neuroblastoma.