Abstract

 Background and Objectives

  WT1 gene encodes a transcription factor that is involved in differentiation and proliferation of hematopoietic precursor cells as well as some other tissues like kidney, ovary, heart, etc. Quantitative assessment of WT1 gene expression is proposed as a useful marker in MRD detection and leukemia management.

 Materials and Methods

  To assess the relevance of this gene, we analysed peripheral blood mononuclear cells of 62 AML patients (new cases) for the expression level of WT1 mRNA using Real-time quantitative RT-PCR. We followed the analysis up to 3 years, depending on patient availability. This study as a fundamental and applicable one was done cross-sectionnaly. Samples were obtained randomly from the AML patients referred to the BMT center, and selection was based on the diagnostic criteria defined by clinical wards. WT1 expression in MNCs of patients was compared with 24 healthy individuals (K562 cells considered to express WT1 gene equivalent to 10⁶).

 Results

 Samples for diagnosis showed significantly high levels of WT1 expression (>80%). After chemotherapy, its expression decreased (diminished about 1-2 log within induction therapy and around 3-4 log after consolidation therapy). There was a noticable correlation between the relative expression levels of WT1 and predicition of relapse (lower than gray zone versus higher than). Patients whose WT1 expression levels remained lower than the gray zone benefit from a better compete remission. On the contrary, 1-6 months prior to overt clinical relapse in 6 patients, their WT1 expression raised to levels upper than gray zone.

 Conclusions

 This study revealed that WT1 is a useful marker for detecting minimal residual disease, assessing chemotherapy effects, and prediciting relapse in AML patients.

 Key words : WT1 gene, Minimal Residual Disease (MRD), PCR