Sequencing analysis of several genes mapped to 9p locus detected the presence of a disease segregating truncation mutation (Q342X) in the intra-flagellar transport protein 74(IFT74) in one independent American family with FTD-ALS.[65] However, no causal IFT74 mutations were identified in conclusively linked FTD-ALS families indicating additional loci (other than VCP and IFT74) for 9p linked FTD-ALS families. This evidence concerns the gene VCP and frontotemporal dementia.