The pathogenic chromosome translocations present in various hematological malignancies result in the formation of fusion genes, which are detected by a reverse transcription-polymerase chain reaction (RT PCR) method. Furthermore, with this method, it is possible to detect minimal residual disease (MRD) sensitively, which is difficult with morphological testing. It has been established that the detection of MRD is important for diagnosis, evaluation of prognosis, and monitoring of leukemia. In particular, quantitative analysis of MRD load transition during the initial phase of treatment is of high prognostic value. At present, however, there is no standard laboratory procedure for leukemia genetic testing. Here, the problems related to external precision management are discussed.