Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) GM2-gangliosidosis, AB variant ?
    ### Response:
    GM2-gangliosidosis, AB variant is a rare inherited disorder that progressively destroys nerve cells (neurons) in the brain and spinal cord.  Signs and symptoms of the AB variant become apparent in infancy. Infants with this disorder typically appear normal until the age of 3 to 6 months, when their development slows and muscles used for movement weaken.
    