Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Nance-Horan syndrome ?
    ### Response:
    Nance-Horan syndrome is a rare genetic disorder that may be evident at birth. It is characterized by teeth abnormalities and cataracts, resulting in poor vision. Additional eye abnormalities are also often present, including a very small cornea and nystagmus.
    