nm23-H1 protein expression in newly diagnosed and relapsed childhood acute lymphoblastic leukemia.

In a retrospective study, immunocytochemistry was used to analyze the cells of 62 newly diagnosed and 28 relapsed childhood acute lymphoblastic leukemias (ALL) for the expression of nm23-H1 protein. Of the 62 newly diagnosed ALL, only 9 cases exhibited positive staining (15%) while 10 of the 28 relapsed ALL did (36%). This difference is statistically significant (P = 0.03, Fisher's exact test). Furthermore, the presence of mutations in the exons 1-5 was investigated by RT-PCR and single-strand conformation polymorphism (SSCP) analysis. No mutations could be detected in either the newly diagnosed or relapsed ALL. This finding suggests that nm23-H1 mutations may be a rare event in ALL.