In acute lymphoblastic leukemia (ALL), the most used techniques for MRD monitoring are MFC, which relies on the identification of aberrantly expressed antigens by leukemic cells, and RQ-PCR analysis, which detects rearranged immunoglobulin (Ig)/T-cell receptor (TCR) genes, or recurrent gene fusions such as BCR-ABL1 in chromosome Philadelphia (Ph) positive patients (1–3). The gene discussed is BCR; the disease is acute lymphoblastic leukemia.