Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Joubert syndrome ?
    ### Response:
    Joubert syndrome is a disorder that affects many parts of the body. The signs and symptoms of this condition vary among affected individuals, even among members of the same family.  The hallmark feature of Joubert syndrome is a brain abnormality called the molar tooth sign, which can be seen on brain imaging studies such as magnetic resonance imaging (MRI).
    