Protrudin (synonym ZFYVE27), a protein localized in acidic endosomes and in the endoplasmic reticulum, encoded by the gene SPG33, previously reported to be mutated (p.G191V) in a single family with an autosomal dominant form of hereditary spastic paraplegia, induces neurite formation by directional membrane trafficking6, 7, 8. This evidence concerns the gene ZFYVE27 and hereditary spastic paraplegia.