The proposed sensor structure consist on the surface functionalization of GCE trough the self-assembly of graphene/chitosan nanocomposite, followed by the electro-polymerization of polyaniline (PANI) and electrodeposition of Au nanoparticles and finally decorated with a functional hairpin structure probe for the detection of BCR/ABL fusion gene of CML. Here, BCR is linked to chronic myelogenous leukemia, BCR-ABL1 positive.