The fused in sarcoma/translocated in liposarcoma (FUS/TLS) gene was initially identified as a component of a fusion pro-oncogene resulting from a chromosomal translocation seen in liposarcomas. FUS/TLS belongs to a sub-family of RNA binding proteins, encoding an N-terminal serine–tyrosine–glycine–glutamine (SYGQ) region, an RNA recognition motif (RRM) flanked by glycine rich (G-rich) regions, a cysteine₂/cysteine₂ zinc finger motif and multiple RGG repeats. The FUS/TLS protein interacts with RNA, single stranded DNA and double stranded DNA, and is involved in unique functions in mRNA processing and transport, transcriptional regulation and maintenance of genomic stability. Recently, several mutations in this gene have been found in amyotrophic lateral sclerosis (ALS) patients. The mutant forms of FUS/TLS exhibit similar pathology to other ALS causative genes, including aberrant cytoplasmic inclusions and an increased FUS/TLS cytoplasmic to nuclear ratio. The FUS/TLS mutations identified in ALS patients suggests that altered RNA metabolism may play a role in ALS pathogenesis.