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p53 Mutation Analysis by Sequencing

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Synonyms

  • CLL

Expected Turnaround Time

10 days



Specimen Requirements


Specimen

Peripheral blood or bone marrow


Volume

10-20 mL peripheral blood or 2-3 mL bone marrow aspirate


Minimum Volume

1 mL whole blood or 1 mL bone marrow


Container

Lavender-top (EDTA) tube or green-top (heparin) tube


Collection

Ship specimen with an ice pack. Specimen should arrive in the laboratory within 5-7 days of collection. If specimen is to be stored prior to shipment, store at 2°C to 8°C. Indicate date and time of collection on the request form.


Storage Instructions

Refrigerate.


Causes for Rejection

Specimen does not meet collection criteria: frozen whole blood, marrow, or cell pellet; leaking tube; clotted blood or marrow; grossly hemolyzed specimen, or otherwise visably degraded; contamination by another specimen; specimens containing suspicious foreign material


Test Details


Use

More than 10% of patients with B-CLL have a dysfunctional p53 gene. Patients may have p53 mutations, a p53 deletion, or both. Mutations and deletions in p53 predict poor survival in B-CLL patients (median survival 6-31 months) versus those patients without p53 abnormalities (median survival of patients with normal karyotype >100 months). Several studies have demonstrated that alkylating agents, purine analogs and some monoclonal therapies are ineffective in treating CLL patients with p53 mutations and/or deletions. Finally, chemotherapy can cause p53 gene alterations, can exhibit new alterations of p53.


Limitations

The assay can detect a mutation present in at least 20% of a B-cell-enriched sample. False positive or negative results may occur for reasons that include genetic variants, blood transfusions, or somatic heterogeneity of the tissue sample.

This test was developed and its performance characteristics determined by Esoterix Genetic Laboratories, LLC. It has not been cleared by the Food and Drug Administration.


Methodology

Samples are enriched for B-cells. Susequently, DNA is isolated from the samples and amplified by polymerase chain reaction (PCR). Exons 5-9 and the flanking intronic regions (-6 and +15) of the TP53 gene are analyzed by bi-directional direct DNA sequencing using capillary gel electrophoresis and fluorescence detection.


References

Olivier M, Eeles R, Hollstein M, Khan MA, Harris CC, Hainaut P. The IARC TP53 database: new online mutation analysis and recommendations to users. Hum Mutat. 2002 Jun;19(6):607-614.12007217
Wattel E, Preudhomme C, Hecquet B, et al. p53 mutations are associated with resistance to chemotherapy and short survival in hematologic malignancies. Blood. 1994 Nov 1;84(9):3148-3157.7949187
Ichikawa A, Kinoshita T, Watanabe T, et al. Mutations of the p53 gene as a prognostic factor in aggressive B-cell lymphoma. N Engl J Med. 1997 Aug 21;337(8):529-534.9262496
Döhner H, Stilgenbauer S, Benner A, et al. Genomic aberrations and survival in chronic lymphocytic leukemia. N Engl J Med. 2000 Dec 28;343(26):1910-1916.11136261
Lozanski G, Heerema NA, Flinn IW, et al. Alemtuzumab is an effective therapy for chronic lymphocytic leukemia with p53 mutations and deletions. Blood. 2004 May 1;103(9):3278-3281.14726385

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