Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pachyonychia congenita ?
    ### Response:
    Pachyonychia congenita (PC) is a rare inherited condition that primarily affects the nails and skin. The fingernails and toenails may be thickened and abnormally shaped. Affected people can also develop painful calluses and blisters on the soles of their feet and less frequently on the palms of their hands (palmoplantar keratoderma).
    