Fluorescent IgH Fingerprinting to Assess Minimal Residual Disease in Childhood B-Lineage ALL

Minimal residual disease (MRD) refers to the presence of clonal cells in the bone marrow at a level below morphological detection. It is possible to detect low levels of bone marrow disease in acute lymphoblastic leukemia (ALL) by flow cytometry, ploidy studies, fluorescent in situ hybridization (FISH), Southern blotting, and reverse transcriptase-polymerase chain reaction (RT-PCR) for specific chromosomal translocations. These techniques, however, suffer from a lack of applicability and/or sensitivity (1 ). Clonal IgH rearrangements are the most applicable clonal markers in B-lineage ALL as they are demonstrable by simple PCR-based techniques in approx 90% of cases (2 -4 ).