Two types of markers, namely the clone-specific markers including T-cell receptor (TCR) gamma, TCR delta, and Ig heavy-chain (IgH) gene rearrangements, and malignancy-specific fusion gene mRNA such as SIL-TAL-1, BCR-ABL, and HRX-partner genes, were investigated by molecular biology techniques in 65 Chinese patients with acute lymphoblastic leukemia (ALL).
MLL (also known as ALL-I, HTRX, or HRX) gene translocations are among the most common chromosomal abnormalities recognized in both B-lineage acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).
If exposure induces the rearrangement of the gene, secondary ALL as well as secondary AML could occur after exposure to these agents, because the type of leukemias with rearranged HRX gene is not limited to AML.
These data indicate that RT-PCR allows the detection of HRX-FEL fusion transcripts in the vast majority of cytogenetically proven and immunophenotypically suspected t(4;11) ALL.
Furthermore, cytogenetic analysis alone failed to detected 36% of HRX rearrangements, suggesting that molecular analysis be performed on all infants with ALL to identify this group of high-risk patients.
The chromosomal breakpoints of t(4;11) translocation of acute lymphoblastic leukemia (ALL) have been recently identified at molecular level and shown to involve the AF4 (FEL) gene on chromosome 4 and the ALL-1 (MLL, Hrx) gene on chromosome 11.