Del(5q) Deletion Probe

Deletion of the long arm of chromosome 5 is the most common rearrangement in AML and MDS. Abnormalities of chromosome 5 are found in 42% of therapy related MDS. The deletions are large with breakpoints occurring in bands between 5q11 and 5q35 and are usually interstitial. Two regions, 5q12-14 and 5q31-33 are hot spots for breakpoints but the common deleted region (CDR) in AML and aggressive MDS cases is within 5q31. Early Growth Response 1 (EGR1) maps to this band3 and loss of the gene may cause tumourigenesis in at least two ways: Firstly, EGR1 directly controls the expression of fibronectin (FN1) through pathways that involve TGFB1 and plasminogen activator-1 (PAI1). Together, FN1 and PAI1 inhibit cancer cell growth. In addition, ERG1 is required for p53- dependent apoptosis through the mediation of Retinoblastoma (RB).

The EGR1 probe, labelled in red, covers a 167kb region of 5q31.2, extending from 91.9kb 3’ of EGR1 to 68.4kb 5’ of the gene. The probe mix also contains a control probe for chromosome 5 at 5p15.31 flanking the marker D5S630.