ALS is marked by abnormal accumulations of a protein named FUS/TLS. In creating fruit flies (Drosophila melanogaster) that carry the human FUS/TLS gene, we've found an economical, easily-studied model of ALS. Our goal with this Packard grant is to understand how the FUS/TLS gene promotes the disease in Drosophila. What we discover, we assume, will shed clearer light on both familial and sporadic ALS in patients.