Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) MECP2 duplication syndrome ?
    ### Response:
    MECP2 duplication syndrome is a condition that occurs almost exclusively in males and is characterized by moderate to severe intellectual disability. Most people with this condition also have weak muscle tone in infancy, feeding difficulties, poor or absent speech, seizures that may not improve with treatment, or muscle stiffness (spasticity).
    