Deletion Probe

Order Number
Package Size
100 µl (10 Tests)



The XL ATM/TP53 locus-specific probe detects deletions in the long arm of chromosome 11 and in the short arm of chromosome 17. The green labeled probe hybridizes to a specific region at 11q22 covering the ATM gene. The orange labeled probe hybridizes specifically to the TP53 gene and flanking regions at 17p13.

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Clinical Details

The prognosis and clinical course of 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 that 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 chronic lymphocytic leukemia (CLL) and are associated with a more aggressive disease.

Clinical Applications

  • Chronic Lymphocytic Leukemia (CLL)
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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.

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Expected Patterns

Expected Pattern 1

Normal Cell:
Two green (2G) and two orange (2O) signals.

Expected Pattern 2

Aberrant Cell (typical results):
One green (1G) and two orange (2O) signals indicating a deletion of an ATM locus.

Expected Pattern 3

Aberrant Cell (typical results): Two green (2G) and one orange (1O) signal indicating a deletion of a TP53 locus.

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  • 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