<prompt> Idiotypic class of antibody is determined by -Fc regionHinge regionCarboxy endAmino end  <response>: An idiotype is a shared characteristic between a group of immunoglobulin or T cell receptor TCR molecules based upon the antigen binding specificity and therefore the structure of their variable region. The variable region of antigen receptors of T cells TCRs and B cells immunoglobulins contain complementarity-determining regions CDRs with unique amino acid sequences Ref: 