Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Megalencephaly ?
    ### Response:
    Megalencephaly, also called macrencephaly, is a condition in which an infant or child has an abnormally large, heavy, and usually malfunctioning brain. By definition, the brain weight is greater than average for the age and gender of the child. Head enlargement may be evident at birth or the head may become abnormally large in the early years of life.
    