This peptide is amino acids 11 to 30 fragment of the human coagulation factor IX (hF.IX). In hemophilia B coagulation factor IX deficiency, lack of endogenous F.IX antigen expression, and other genetic factors may increase the risk of inhibitory antibody formation to functional coagulation factor IX. Formation of inhibitory antibodies is a serious complication of protein or gene replacement therapy for hemophilias. This peptide was created to develop a protocol for reducing inhibitor formation in gene therapy.