11q Deletions in Hematological Malignancies

Structural aberrations involving 11q are among the most common aberrations in a number of hematological malignancies. Most of the aberrations, such as translocations and deletions, often harbor a breakpoint at 11q23, which suggests that this region might contain a tumor suppressor gene important for the genesis of lymphoproliferative disorders. Interestingly, deletions are concentrated only in some subtypes of hematological malignancies, where they are detected at a relatively high frequency. In B-cell chronic lymphocytic leukemia (B-CLL), deletions have been detected in 20-30% of the cases, whereas almost half of the mantle cell lymphomas (MCL) show deletion at 11q23 in fluorescence in situ hybridization analysis. In T-cell prolymphocytic leukemia (T-PLL), deletions involving the region 11q23.3-23.1 have also been detected to be frequent. In B-cell chronic lymphocytic leukemia, 11q deletion is associated with more rapid disease progression and poor survival in a younger subgroup of patients. The putative tumor suppressor genes have remained unrevealed until recently, when the ATM gene was found to carry mutations in cases with deletion in B-CLL, MCL and T-PLL. These data suggest that 11q deletions and dysfunction of the ATM gene might have significance in the tumorigenesis of certain subsets of hematological malignancies. Importance of 11q deletion as a diagnostic marker needs to be further studied in a larger series of patients. Another issue that remains to be investigated is the involvement of other target genes in the deletion.