TCRB, 7q34, Red
TCRB, 7q34, Green
The TCRB product consists of a 177kb probe, labelled in red, covering the centromeric end of the TRB gene, including the D7S2473 marker and a green probe covering a 133kb region located telomeric to the TRB gene, including the SHGC-81465 marker.
Chromosomal translocations with breakpoints in beta T-cell receptor (TCR) gene loci at 7q34 are recurrent in several T-cell malignancies including T-cell acute lymphoblastic leukaemia (T- ALL)1.
T-cell acute lymphoblastic leukaemia (T-ALL) is an aggressive malignancy of the lymphoblasts committed to the T-cell lineage and represent 15% of childhood and 25% of adult ALL2,3. Karyotyping reveals recurrent translocations that activate a small number of oncogenes in 25-50% of T-ALLs but with FISH further cryptic abnormalities can be revealed2.
The most common chromosomal rearrangements, found in about 35%2 of T-ALLs, involve the alpha and delta T-cell receptor loci (TRA and TRD) at 14q11.2, the beta TCR locus (TRB) at 7q34 and the gamma TCR (TRG) at 7p14. In most cases the juxtaposition of oncogenes next to the TCR regulatory sequences leads to the deregulated expression of these genes2,4,5.
TRB at 7q34 is rearranged with the genes TLX1 at 10q24, HOX cluster at 7p15, LYL1 at 19p13, TAL2 at 9q32, LCK at 1p34 and NOTCH1 at 9q34 via the t(7;10)(q34;q24); t(7;7)(p15;q34); t(7;19)(q34;p13); t(7;9)(q34;q32); t(1;7)(p34;q34) and t(7;9)(q34;q34) translocations respectively2.
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