Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Greenberg dysplasia ?
    ### Response:
    Greenberg dysplasia is a severe condition characterized by specific bone abnormalities in the developing fetus. This condition is fatal before birth.  The bones of affected individuals do not develop properly, causing a distinctive spotted appearance called moth-eaten bone, which is visible on x-ray images.
    