Gene expression profiling has discriminated between sporadic microsatellite instable (MSI) and microsatellite stable (MSS) colorectal cancers (CRCs), whereas the expression pattern of familial colorectal cancer type X (FCCTX) and Lynch syndrome (LS) associated CRCs remain largely unknown. The purpose of this study is to use gene expression profiling of formalin-fixed paraffin-embedded (FFPE) tumor specimens from FCCTX, LS and sporadic CRC as a control to detect expression patterns and to identify signaling pathways differing between FCCTX and LS tumors. Overall design: RNA extracted from 132 FFPE specimens (40 FCCTX, 42 LS, 50 sporadic) were profiled for differential gene expression by the whole genome cDNA-mediated annealing, selection, extension, and ligation (WG-DASL) assay containing 18626 genes.