Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Familial mixed cryoglobulinemia ?
    ### Response:
    Familial mixed cryoglobulinemia is a rare condition that is characterized by the presence of abnormal proteins (called cryoglobulins) in the blood. These proteins clump together into a "gel-like" consistency at low temperatures, which can lead to inflammation, blocked blood vessels, and a variety of health problems.
    