<prompt> Answer this question truthfullyWhat is the name of the autoantibody that targets the Fc portion of IgG antibodies in the body, and what class of autoantibody does it belong to?  <response>: <reason> The autoantibody that targets the Fc portion of IgG antibodies in the body is called rheumatoid factor, and it belongs to the class of IgM autoantibodies. 