ATM Deletion Probe

The protein kinase ATM (Ataxia- Telangiectasia Mutated) gene located in 11q22.3 is frequently deleted in cases of B-CLL. The ATM gene is an important checkpoint gene involved in cell damage management and its function is to assess the level of DNA damage that the cell has received and to attempt repair by phosphorylating key substrates involved in DNA repair. Recently, the ATM/p53 interaction in B-CLL has been shown to have an important impact on the proliferation or otherwise of the cancer. It has been shown that ATM concurrently enhances the phosphorylation of p532 should the damage to the cell be so great that it should be destroyed by apoptosis (which is mediated by p53). Deletion of ATM therefore removes this checkpoint activity and hence activation of TP53 gene. Thus, there is no attempt at repairing damaged cells and no apoptosis of these cells despite the p53 protein being present. In the absence of ATM, damaged cells are allowed to proliferate. Deletions of ATM and TP53 are the most serious rearrangements involved in CLL and detection of deletions of these genes provides very important information as to the therapy choices for such patients especially since deletions of 11q22.3 and therefore ATM provides a poor prognosis.

The ATM gene probe measures 158kb, labelled in red, which covers the 5’ region of NPAT and the 3’ region of ATM up to D11S3347. The probe mix also contains a control probe for the 11 centromere (D11Z1).