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CTNNB1 Mutational Analysis

Indication

Somatic mutations in CTNNB1 (also known as beta-catenin), primarily involving exon 3 (codons 5 and 70), have been reported in desmoids tumors, adrenal cortical carcinoma, biliary tract adenocarcinoma, medulloblastoma, endometrial adenocarcinoma, ovarian endometroid carcinoma, diffuse large B-cell lymphoma, NK-T cell lymphoma, Wilms tumor, hepatocellular carcinoma, pancreatic tumors, pituitary craniopharyngioma, salivary gland basal cell adenoma, malignant melanoma, intestinal adenocarcinoma, and, papillary and anaplastic carcinoma of thyroid.

Clinically, CTNNB1 mutations can provide evidence of an oncogenic molecular abnormality in appropriate clinicopathologic settings. The molecular diagnostics laboratory (MDL) has developed a clinical assay using PCR-based DNA sequencing (Sanger sequencing) of exon 3 of CTNNB1 to test for mutations in codons 5 to 70 in formalin-fixed paraffin-embedded tumor samples.

Methodology

Mutations are tested using PCR-based bi-directional DNA sequencing (Sanger sequencing)  for codons 5-70.  This assay is also available on Next Gen Sequencing panel for Solid Tumor Testing Exon 3, codons 13, 21, 22-38, 41, and 45.

Test Parameters

Exon 3 of CTNNB1 is sequenced to detect mutations in codons 5 to 70. The lower limit of detection is approximately one cell bearing the mutation per five cells (20%) for Sanger Sequencing.

Turnaround Time

10 days

Sample Requirements

Formalin-fixed, paraffin embedded tissue blocks or 10 unstained slides containing adequate amounts of tumor to be analyzed (see above sensitivity), with areas to be tested clearly indicated on the slides/block. Comparison of normal and tumor, or several different areas of tumor can be done, for an additional charge.

Please provide a copy of the corresponding pathology report.

CPT Codes

81403

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