Home
HelpTest ID P53CA Hematologic Neoplasms, TP53 Somatic Mutation, DNA Sequencing Exons 4-9
Useful For
Evaluating chronic lymphocytic leukemia patients at diagnosis or during disease course for the presence of TP53 gene mutations indicating high risk of disease progression and adverse outcome
This test is complementary to FISH analysis for the 17p- abnormality, but more appropriately identifies the presence of mutational alteration and gene inactivation in tumor cells. For hereditary (germ line) TP53 mutation syndrome testing, see TP53Z / TP53 Gene, Full Gene Analysis.
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CKP53 | CKP53 Protocol, B | No | No |
Testing Algorithm
Flow cytometry CKP53 / CKP53 Protocol, Blood may be performed on peripheral blood samples to verify diagnosis of chronic lymphocytic leukemia (CLL) and determine the % B-cells in the sample prior to TP53 testing. See TP53 Sequencing Testing Algorithm in Special Instructions.
Special Instructions
Method Name
Polymerase Chain Reaction (PCR) and Sanger Sequencing
(PCR is utilized pursuant to a license agreement with Roche Molecular Systems, Inc.)
Reporting Name
TP53 gene somatic mutation analysisSpecimen Type
VariesThe following information is required:
1. Pertinent clinical history
2. Clinical or morphologic suspicion
3. Date of collection
4. Specimen source
Forms:
1. Molecular Hematopathology Patient Information: B-Cell Chronic Lymphocytic Leukemia (CLL) for IGVH and/or TP53 Somatic Mutation Testing in Special Instructions
2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request Form (T726) with the specimen
(http://www.mayomedicallaboratories.com/it-mmfiles/hematopathology-request-form.pdf)
Blood and bone marrow specimens must arrive within 96 hours of collection.
Submit only 1 of the following specimens:
Specimen Type: Blood (preferred)
Container/Tube: Lavender top (EDTA), yellow top (ACD solution B), or green top (heparin)
Specimen Volume: 10 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube.
3. Label specimen as blood.
Specimen Stability Information: Ambient <96 hours
Specimen Type: Bone marrow
Container/Tube: Lavender top (EDTA), yellow top (ACD solution B), or green top (heparin)
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Send specimen in original tube.
3. Label specimen as bone marrow.
Specimen Stability Information: Ambient <96 hours
Specimen Type: Tissue
Container/Tube: Plastic container
Specimen Volume: 100 mg
Collection Instructions: Freeze immediately after collection.
Specimen Stability Information: Frozen
Specimen Minimum Volume
5 mL peripheral blood; 2 mL bone marrow
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | 4 days |
| Refrigerated | 4 days |
Clinical Information
Patients with chronic lymphocytic leukemia (CLL) have variable disease course influenced by a series of tumor biologic factors. The presence of chromosomal 17p- or TP53 gene mutation confers a very poor prognosis to a subset of CLL patients, both at time of initial diagnosis, as well as at disease progression, or in the setting of therapeutic resistance. TP53 gene mutation status in CLL has emerged as the single most predictive tumor genetic abnormality associated with adverse outcome and poor response to standard immunochemotherapy; however, patients can be managed with alternative therapeutic options. Although the prognostic relevance of acquired TP53 gene mutation is best studied for CLL, similar findings are also reported for other hematologic malignancies including low grade B-cell lymphoma, diffuse large B-cell lymphoma, and some types of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Therefore, while this test has been developed to be primarily focused on high risk CLL patients, p53 gene sequencing analysis can also be performed in additional neoplasms, as clinically indicated. This test is NOT intended for the evaluation of patients suspected of having an inherited, or germ line TP53 mutation cancer syndrome (eg, Li Fraumeni syndrome); if this is intended as a clinical indication, see TP53Z / TP53 Gene, Full Gene Analysis.
Reference Values
Mutation(s) present or absent as compared to a reference sequence of the normal TP53 gene
Cautions
The analytical sensitivity of the assay can be affected by the absolute B-cell number in the peripheral blood or tissue sample, as well as the often subclonal nature of this tumor genetic abnormality. The assay attempts to compensate in part for this by performing an initial screening flow cytometry to assess B-cell quantity and by performing the cell enrichment step (for the peripheral blood specimens only) to isolate relatively pure CD19+ B-cells for analysis. Nevertheless, the nature of the Sanger sequencing method is such that typical reproducible analytic sensitivity will be in the order of 25% mutant allele burden.
Because optimal cell enrichment is dependent on the absolute B-cell quantity, samples with very low WBC and/or initial %B cells (determined from flow cytometry or WBC automated cell count) will likely result in poor assay performance and inability to detect possible TP53 gene mutations in the tumor population.
Day(s) Performed
Monday, Wednesday
Report Available
7 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
81405-TP53 (tumor protein 53) (eg, tumor samples), full gene sequence or targeted sequence analysis of >5 exons.