The Del(5q) Plus Tri-Colour Deletion Probe mix consists of three distinct probes. The green probe (378kb) covers the CDC25C and EGR1 genes, along with their flanking regions that include the RH68817 and D5S500 markers. The red probe set (147kb, 155kb and 189kb) locates between the D5S1708 and D5S551 markers and includes the CSF1R, PDGFRB, TCOF1 and RPS14 genes. The aqua probe set (224kb and 367kb) locates between the markers RH76617 and RH92681 and includes the genes TERT, CLPTM1L, SLC6A3 and SDHAP3.
Deletions of the long arm of chromosome 5 are one of the most common karyotypic abnormalities in myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML) with myelodysplasia related changes1,2.
A subset of MDS patients with del(5q) as a sole cytogenetic abnormality, or with a single additional abnormality not involving chromosome 7, have a consistent set of clinical features, termed the 5q- syndrome1. It is the only MDS subtype defined cytogenetically in the World Health Organization classification system. This clinical entity with <5% blasts has a more favourable prognosis. However, patients with del(5q) associated with other cytogenetic abnormalities, or with excess blasts, have an inferior survival2,3.
In contrast to de novo MDS, prognosis of AML with del(5q) is generally unfavourable, especially when seen as a part of complex karyotype4. Deletion of 5q is also commonly seen in treatment related t-MDS and t-AML where prognosis is particularly poor1.
Two chromosomal regions have been mapped on chromosome 5q in MDS and AML. One common deleted region, at 5q33, is associated with the 5q- syndrome. Another, more proximal region located at 5q31, has been linked to a more aggressive form of MDS and AML and is often accompanied by additional cytogenetics abnormalities and a poorer prognosis1,3,5.
The CytoCell Del(5q) Plus Tri-Colour Deletion Probe will detect deletions of EGR1 (early growth response 1), a tumour suppressor gene at 5q31. EGR1 has been shown to act through haploinsufficiency to initiate the development of MDS/AML6. The probe will also detect deletions of RPS14 (ribosomal protein S14) at 5q33.1, patients with MDS with del(5q) are haploinsufficient for RPS14 which leads to impairment of ribosome biogenesis and affects translation of genes and activation of proteins involved in differentiation and apoptosis4. The TERT (telomerase reverse transcriptase) gene probe at 5p15.3 will help distinguish cases with del(5q) from those with monosomy 5.
Not only do CytoCell offer an extensive range of high-quality FISH probes, the customer support is also excellent — providing fast access to all the probes I need. The probes are highly consistent with bright signals allowing easy scoring of results.
Dr Eric Crawford
Senior Director, Genetics Associates Inc., USA