Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Ulcerative Colitis ?
    ### Response:
    Ulcerative colitis (UC) is a disease that causes inflammation and sores, called ulcers, in the lining of the rectum and colon. It is one of a group of diseases called inflammatory bowel disease.    UC can happen at any age, but it usually starts between the ages of 15 and 30.
    