CPT® Code 81309

PIK3CA (phosphatidylinositol-4, 5-biphosphate 3-kinase, catalytic subunit alpha) (eg, colorectal and breast cancer) gene analysis, targeted sequence analysis (eg, exons 7, 9, 20)

The CPT® Code 81309 pertains to the molecular genetic testing of the PIK3CA gene, which is crucial for identifying specific mutations associated with certain types of cancer, particularly colorectal and breast cancer. The PIK3CA gene is located on the long (q) arm of chromosome 3 at position 26.32 (3q26.32) and is responsible for encoding the P110 alpha (p110a) protein, which serves as the catalytic subunit of the phosphatidylinositol-4,5-biphosphate-3-kinase enzyme. This enzyme plays a significant role in various signaling pathways that regulate essential cellular processes, including growth, apoptosis (cell death), and proliferation. The targeted sequence analysis focuses on specific exons of the PIK3CA gene, namely exons 7, 9, and 20, where mutations can have implications for treatment response and prognosis in patients diagnosed with colorectal and breast cancers. The analysis involves extracting genomic DNA (gDNA) from formalin-fixed paraffin-embedded (FFPE) tissue, core needle biopsy samples, or resected tissue slides. This DNA is then amplified using polymerase chain reaction (PCR) techniques and analyzed through targeted sequencing methods, such as Sanger sequencing or next-generation sequencing, to detect mutations that may influence clinical outcomes.