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PIK3CA Mutation Analysis

Indication

 

Mutations in the PIK3CA gene have been identified in carcinomas arising from colon, breast, ovary, liver, stomach, and lung as well as in glioblastomas.  Evidence suggests that such mutations lead to constitutive activation of the PI3K pathway.  Mutations in PIK3CA are clustered and occur mainly in the helical (exon 9) and kinase (exon 20) domains of the protein.

Recent studies suggest that mutations in PI3KCA are associated with a more aggressive clinical course.  To facilitate identification of patients who may benefit from a PI3K-targeted therapy approach, the Molecular Diagnostic Laboratory has developed a PCR primer extension-based assay to screen for mutations in the PIK3CA gene.

Methodology

 

Sanger sequencing is performed for exons 9 and 20 of the PIK3CA gene..  This assay is also available on the Next Gen Sequencing panel (CMS46) for solid tumor testing.

 

Test Parameters

 

The DNA primer extension assay is designed to screen for the following frequently reported mutations (mutational hot spots) in the PIK3CA gene.  exon 1 (p.Q60K, p.R88Q, p.E110K and p.K111N), exon 4 (p.N345K), exon 6 (p.S405S), exon 7 (p.E418K, p.C420R, p.E453K), exon 9 (p.P539R, p.E542(base 1 and 2), p.E545 (all 3 bases) and p.Q546 (base 1 and 2)), exon 18 (p.F909L) and exon 20 (p.Y1021(base 1 and 2), p.T1025 (base 1), p.M1043I, p.M1043V, p.A1046V, p.H1047Y,p.H1047, p.G1049R).

This assay with focus on reported mutation hot spots in multiple exons replaces the current Sanger sequencing based assay that detected mutations only in exons 9 and 20.

The lower limit of detection is approximately 20%.

 

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 additional charge.
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