Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Lissencephaly ?
    ### Response:
    Lissencephaly, which literally means "smooth brain," is a rare, gene-linked brain malformation characterized by the absence of normal convolutions (folds) in the cerebral cortex and an abnormally small head (microcephaly). In the usual condition of lissencephaly, children usually have a normal sized head at birth.
    