TCL1, 14q32.13, Red
TCL1, 14q32.2, Green
The TCL1 product consists of a 138kb probe, labelled in red, located centromeric to the TCL1A and TCL1B genes, including the GLRX5 gene and the D14S62 marker, and a green probe covering a 124kb region located telomeric to these genes, including the D14S131 marker.
The TCL1A (T-cell leukemia/lymphoma 1A) and TCL1B (T-cell leukemia/lymphoma 1B) genes at 14q32 have been shown to be dysregulated through close juxtaposition of enhancer elements of the T-cell receptor (TCR) genes1.
Dysregulation of gene transcription is a feature of all acute leukaemias. In T-cell neoplasms, this is brought about by altered expression of normal transcription factor proteins, often as a consequence of chromosomal rearrangements placing these genes into close proximity of the promoter and enhancer elements of the TCR genes: TRA and TRD at 14q11.2, TRB at 7q34 and TRG at 7p142,3.
In T-cell prolymphocytic leukaemia (T-PLL) the T-cell Leukaemia 1A/1B gene cluster on chromosome 14q32 has been shown to be involved in a number of different chromosomal rearrangements, including the t(14;14)(q11;q32) and inv(14)(q11;q32), which bring elements of the cluster into close juxtaposition to, and under the control of, the TCR gene promoters and enhancers. There are two breakpoint regions in the gene cluster, each of which are observed in different neoplasms, though both are involved in either the inv(14) or t(14;14). Breakpoints are concentrated in regions centromeric and telomeric to the TCL1A, TCL6 and TCL1B genes4.
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