Genetic rearrangements in relation to immunophenotype and outcome in T-cell acute lymphoblastic leukaemia.

Mutually exclusive oncogenic rearrangements may delineate specific T-cell acute lymphoblastic leukaemia (T-ALL) subgroups, and so far at least 4 molecular-cytogenetic subgroups have been identified, i.e. the TAL/LMO, the TLX1/HOX11, the TLX3/HOX11L2 and the HOXA subgroups. A fifth group with an immature immunophenotype that can be predicted by an early T-cell precursor signature has also been identified, and has been associated with poor outcome. The association of these subgroups with the expression of specific immunophenotypic markers reflecting arrest at specific T-cell developmental stages will be reviewed. These strong associations urge the need to extensively study oncogenic rearrangements and immunophenotypic markers in relation to outcome for future treatment protocols, both for paediatric as well as adult T-ALL patients.