E2A/PBX1, MLL/AF4, BCR/ABL (M-BCR), BCR/ABL(m-BCR) Gene Rearrangements in Acute Lymphoblastic Leukemia in Iranian Children

The following observation was primarily based on the study of gene fusion in blood and bone marrow cells taken from 68 Iranian children with acute lymphoblastic leukemia (ALL), to compare with healthy population.
Peripheral blood and bone marrow samples obtained from patients with ALL were immunophenotyped to determine the lineage and the level of differentiation. With reverse transcriptase-polymerase chain reaction (RT-PCR), the RNA molecules were analyzed according to Van Dongen et al. protocol to detect fused genes in cell population.
Leukemic cell type was identified by cytochemical stains and classified on the basis of FAB classification. Nonetheless the frequencies of E2A/PBX1, MLL/AF4, BCR/ABL (M-BCR) and BCR/ABL(m-BCR) gene transcripts were 1.5%, 0%, 0% and 4.4% respectively. The positive case of E2A/PBX1 fusion gene had an early pre B and 3 BCR/ABL (m-BCR). Positive cases had an early pre B and pre-B ALL immunophenotype.
Early pre-B cells were the most common types in our patients. The RT-PCR was shown to be an ideal method for detecting hybrid transcripts and to estimate the prevalence of the fusion genes in ALL patients. The frequency of these fusion genes in Iranian pediatric ALL patients were found to be similar to some developed countries. Thus, their presence does not seem to be predictive of increasing malignancy, but rather it can challenge the prognostic significance of these rearrangements.