Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) primary sclerosing cholangitis ?
    ### Response:
    Primary sclerosing cholangitis is a condition that affects the bile ducts. These ducts carry bile (a fluid that helps to digest fats) from the liver, where bile is produced, to the gallbladder, where it is stored, and to the small intestine, where it aids in digestion.
    