Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Brachydactyly type B ?
    ### Response:
    Brachydactyly type B is a very rare genetic condition characterized by disproportionately short fingers and toes. The ends of the second and fifth fingers are usually underdeveloped with complete absence of the fingernails. The thumb bones are always intact but are frequently flattened and/or split.
    