P53 is a tumor suppressor gene, located on chromosome 17p13.1, which stops cell division when DNA damage is present, thus allowing DNA repair to occur before cell division. When p53 does not function normally due to gene mutations or a gene deletion, cancer cells can accumulate.
Over 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, such that even if not present at initial diagnosis, refractory CLL can exhibit new alterations of p53.
The p53 mutation assay incorporates PCR amplification and bidirectional sequencing of p53 exons 5-9 along with their respective flanking splice sites. The assay can detect a mutation present in at least 20% of a B-cell enriched sample. FISH analysis is also available to detect a deletion of the 17p chromosome.
Information Sheet - 17p Deletion & p53 Mutation Analysis (PDF)
CPT Codes:
83891(1), 83898(3), 83892(2), 83909(3), 83904(3), 83912(1)
Specimen Requirements:
- 10-20 ml peripheral blood in EDTA (lavender-top) tube or sodium heparin (green-top) tube.
- 2-3 ml bone marrow aspirate in EDTA (lavender-top) tube or sodium heparin (green-top) tube.
Turnaround Time:
7-10 days
Client Services:
Oncology/Pathology
800-447-5816
Specimen Services/Pickup:
877-246-1226