Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Nuclear Gene-Encoded Leigh Syndrome ?
    ### Response:
    Nuclear gene-encoded Leigh syndrome is a progressive neurological disease. It usually first becomes apparent in infancy with developmental delay or regression. Rarely, the disease begins in adolescence or adulthood. Symptoms progress to include generalized weakness, lack of muscle tone, spasticity, movement disorders, cerebellar ataxia, and peripheral neuropathy.
    