Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Lujan syndrome ?
    ### Response:
    Lujan syndrome is a condition characterized by intellectual disability, behavioral problems, and poor muscle tone (hypotonia). Affected people also tend to have characteristic physical features such as a tall and thin body; a large head (macrocephaly); and a thin face with distinctive facial features (prominent top of the nose, short space between the nose and the upper lip, narrow roof of the mouth, crowded teeth and a small chin).
    