DDC and neuroblastoma: Two sets of five markers (CHRNA3, DDC, GAP43, PHOX2B, TH) for BM samples and five markers (CHRNA3, DBH, DDC, PHOX2B, TH) for PB samples were identified by comparing serial analysis of gene expression (SAGE) libraries of neuroblastoma and healthy tissues followed by qPCR analysis of 56 neuroblastoma tumors, 51 control BM samples, and 37 control PB samples (109, 124).