Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) gnathodiaphyseal dysplasia ?
    ### Response:
    Gnathodiaphyseal dysplasia is a disorder that affects the bones. People with this condition have reduced bone mineral density (osteopenia), which causes the bones to be unusually fragile. As a result, affected individuals typically experience multiple bone fractures in childhood, often from mild trauma or with no apparent cause.
    