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 a motor neuron disease characterized by progressive weakness and stiffness of muscles in the arms, legs, and face. Initial symptoms usually occur within the first 2 years of life and include weakness of the legs, leg muscles that are abnormally tight and stiff, and eventual paralysis of the legs.
    