Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Gerstmann-Straussler-Scheinker Disease ?
    ### Response:
    Gerstmann-Straussler-Scheinker disease (GSS) is an extremely rare, neurodegenerative brain disorder. It is almost always inherited and is found in only a few families around the world. Onset of the disease usually occurs between the ages of 35 and 55. In the early stages, patients may experience varying levels of ataxia (lack of muscle coordination), including clumsiness, unsteadiness, and difficulty walking.
    