The hereditary spastic paraplegias (HSP) are characterized by spastic gait with weakness in the
legs and additional neurological or extra-neurological signs in "complicated" forms.
The past two decades have witnessed major advances in our understanding of their molecular bases with the
identification of a plethora of loci and the cloning of several SPG genes. Combined genetic and clinical
information has permitted a modern, molecularly-driven classification and an improved diagnosis, with several
new data on the possible disease mechanisms. Further heterogeneity will rapidly emerge with the diffusion of
next-generation sequencing platforms and, under the shadow of common themes in the pathogenesis, new
therapeutic options will likely emerge for a great number of patients.