IGH Breakapart Probe

In ALL, this is most notably involved in rearrangements involving the MYC oncogene as a result of the t(8;14) translocation. However, less common rearrangements of the IGH gene are most often seen in T-ALL but can also be found in B-ALL. There are a number of stereotypical translocations involved in each of the two diseases and more are being described regularly. In T-ALL, for example, IGH is observed in the t(14;14)(q11;q32) translocation (or inv(14)(q11q32) rearrangement) and is found in T-cell leukaemia associated with ataxia-telangiectasia (AT); however, rare reports have indicated that this abnormality also occurs in B-ALL. The recurrent t(14;19)(q32;q13) translocation associated with chronic Bcell lymphoproliferative disorders, such as atypical CLL, has also been shown to occur in B-ALL and results in the juxtaposition of the IGH and BCL2 genes and subsequent over expression of BCL33. More recently, a report suggested the involvement of IGH in a novel cryptic translocation in paediatric T-cell Acute Lymphoblastic Leukaemia (T-ALL), which also involved HOX11L2 or CSX on 5q35, brought about by a t(5;14)(q35;q32) translocation. In CLL, around 20% of cytogenetically abnormal CLL patients have a detectable 14q+ marker chromosome. The markers are derived from reciprocal translocations involving a number of fusion partners from different chromosomes that fuse with the IGH gene at 14q32. Involvement of chromosomes 1, 2, 5, 6, 7, 8, 9, 11, 12, 13, 14, 17, 18, 19 and 22 have been described and the two most common translocations are IGH/BCL2 involving the t(14;18) translocation and IGH/CCND1 involving the t(11; 14) translocation.

With all these rearrangements having breakpoints within the IGH gene, we have designed a split probe set for IGH, which can detect any rearrangement, which involves the splitting of the IGH gene in the region between the Constant and Variable segments, thereby identifying the IGH translocation partner chromosome in the less common rearrangements of this gene.

The Constant region of the gene is labelled in red whilst the Variable segment is labelled in green. The normal situation is represented by fusion or close juxtaposition of the red and green signals (2Y) whilst a rearrangement of the gene is detectable by separate green and red signals (1Y, 1G, 1R). This probe set will detect such rearrangements in interphase cells as well as in dividing cells.