XL ATM/TP53 consists of a green-labeled probe hybridizing to the ATM gene region at 11q22.3 and an orange-labeled probe hybridizing to the TP53 gene region at 17p13.

Probe maps are created in accordance with the intended purpose of the product. Solid colored bars do not necessarily indicate that the probe fully covers the indicated genomic region. Therefore, caution is advised when interpreting results generated through off-label use. Probe map details based on UCSC Genome Browser GRCh37/hg19. Map components not to scale. Further information is available on request.

The prognosis and clinical course of chronic lymphocytic leukemia (CLL) are heterogeneous. Conventional banding techniques in CLL are hampered by the low mitotic index of the neoplastic cells. The introduction of interphase cytogenetics using fluorescent in situ hybridization (FISH) has greatly increased the sensitivity of cytogenetic analyses. With FISH, abnormalities can be detected in more than 80% of patients by using a 4-probe panel for the detection of trisomy 12q13-15 and deletions 13q14, 17p13, and 11q22-23. An additional 10% of patients can be shown to carry a 6q21 deletion, 14q32 translocation, and partial trisomy 3q or 8q.

TP53 is a tumor suppressor gene which stops cell division when DNA damage is present. Loss of TP53 at 17p13 is a powerful predictor of resistance to therapy with purine analogues and alkylating agents, and of poor prognosis in CLL. Chromosome 11q22.3-23.1 deletions involving the ataxia telangiectasia mutated (ATM) locus are detected at diagnosis in 15 - 20% of cases of B-cell CLL and are associated with a more aggressive disease.

Clinical Applications

• Chronic Lymphocytic Leukemia (CLL)

XL ATM/TP53 hybridized to bone marrow cells. Four interphases are shown of which two show a normal signal pattern. The two other interphases show aberrant signal patterns with a deletion of ATM in one cell and a deletion of TP53 in the other one.

• Doehner et al (2000) N Engl J Med 343:1910-1916
• Stilgenbauer et al (2002) Leukemia 16:993-1007
• Gunn at al (2008) J Mol Diagn 10:442-451