Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) infantile-onset ascending hereditary spastic paralysis ?
    ### Response:
    Infantile-onset ascending hereditary spastic paralysis is one of a group of genetic disorders known as hereditary spastic paraplegias. These disorders are characterized by progressive muscle stiffness (spasticity) and eventual paralysis of the lower limbs (paraplegia).
    