Text Box: ESTABLISHMENT AND APPLICATION OF BCR/ABL FUSION GENE RT-PCR IN SITU DETECTION METHOD Zhou Dongfeng, Meng Pu Department of Pediatrics, Union Hospital of Tongji Medical College, Huazhong Science And Technology University, Wuhan, China Objective: To explore a new method of detecting BCR/ABL fusion gene. Methods: After cellular fixation and digestion，reverse transcription and amplification were performed directly inside the cells in a testtube. When the reaction terminated, in situ observation was carried out under microscope. Results: The expression signals of BCR/ABL fusion gene were dark violet-blue or brown precipitates. Positive rate in 36 CML cases reached 94.4%. 3 of 5 Ph CML cases were detected with the expression of BCR/ABL gene. The gene expression levels in blast crisis and accelerated phase were significantly higher than in the chronic phase. Conclusion: It was suggested that RT-PCR in situ, with high sensitivity and specificity, is a simple and rapid method detecting the expression of BCR/ABL gene, both qualitatively and quantitatively .It provided a direct and accurate in the diagnosis, differential diagnosis and predition the disease progress of CML. 2380