MRD monitoring in chromosome Philadelphia-positive (Ph’-positive) B-ALL is based on quantification of BCR-ABL1 transcript using QT-PCR; a recent Italian study applied ddPCR to patients enrolled into the GIMEMA LAL2116 trial, showing optimal sensitivity (1 × 10−5–5 × 10−6) and specificity (near to 100%). The gene discussed is ABL1; the disease is acute lymphoblastic leukemia.