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MYD88 Codon 265 Mutational Analysis

Indication

The MYD88 or myeloid differentiation primary response 88 gene, is located on the short arm of chromosome 3 at position 22 (3p22), and encodes for an adapter protein that acts as a signal transducer in the IL-1, IL-18 and Toll-like receptor signaling pathways, as part of the innate immune response.

Mutations in MYD88 are seen in lymphoid neoplasms and commonly involve substitution of leucine (L) at codon 265 by proline (P). The MYD88 p.L265P mutation is shown to occur at different frequency in subclasses of B-cell lymphoproliferative disorders suggesting its utility as a diagnostic marker. The MYD88 p.L265P mutation is reported in 80 to 100% cases of lymphoplasmacytic lymphoma (LPL)/Waldernstrom Macroglobulinemia (WM), a neoplasm of small B-lymphocytes, plasmacytoid lymphocytes and plasma cells that often presents a diagnostic challenge due to its clinical, morphologic and immunophenotypic overlap with other B-cell neoplasms such as marginal zone B-cell lymphoma, multiple myeloma, and IgM monoclonal gammopathy of undetermined significance. Recent studies have revealed that the MYD88 p.L265P mutation can be used as a diagnostic biomarker for LPL and help in the differential diagnosis from other morphologically similar B-cell neoplasms. Similarly, approximately 30-40% of activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) show MYD88 p.L265P mutation compared to <10% cases of the germinal center B-cell-like (GCB) subtype. The molecular diagnostics laboratory (MDL) has developed a pyrosequencing-based sequencing assay to assess for the p.L265P mutation in MYD88 to be used as a diagnostic adjunct to morphologic and immunophenotypic assays for selected B-cell lymphoproliferative disorders.

Methodology

This assay is available as PCR-based pyrosequencing of DNA to examine codon 265 of the MYD88 gene.

Test Parameters

The assay is designed to detect the leucine to proline mutation in codon 265 of MYD88. The lower limit of detection is approximately 5-10% mutation bearing cells in the sample tested.

Turnaround Time

10 days

Sample Requirements

10 mL peripheral blood, 2-5mL bone marrow aspirate, or 5µg purified DNA. Tissue sections may also be utilized for testing purposes, and testing requires formalin-fixed, paraffin embedded tissue blocks or 4-10 unstained tissue sections on glass slides along with 1 H&E-stained section containing adequate amounts of tumor to be analyzed (see above sensitivity), with areas to be tested clearly indicated on the slides/block. Please provide a copy of the corresponding pathology report.

CPT Codes

81479

Additional charges may apply for tissue extraction.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.


© 2014 The University of Texas MD Anderson Cancer Center