A novel growth factor, neurturin, is disclosed and the human and mouse amino acid sequences are identified. Human and mouse neurturin genomic DNA sequences have been cloned and sequenced and the respective cDNA sequences identified. The subcloning into vectors and the preparation of cells stably transformed with the vectors are also disclosed. In addition, methods for treating degenerative conditions, tumor cells and obesity; methods for detecting gene alterations and methods for detecting and monitoring patient levels of neurturin are provided. Methods for identifying additional members of the neurturin-GDNF family of growth factors are also provided.