CPT® Code 81306

The CPT® Code 81306 pertains to the molecular genetic testing of the NUDT15 (nudix hydrolase 15) gene, specifically focusing on the identification of common variants such as *2, *3, *4, *5, and *6. This gene analysis is crucial for understanding how certain individuals metabolize thiopurine drugs, which are commonly prescribed for various medical conditions, including malignant diseases like acute lymphoblastic leukemia, autoimmune disorders such as rheumatoid arthritis and inflammatory bowel disease, dermatological issues, and for solid organ transplant recipients to prevent organ rejection. The NUDT15 gene is situated on the long (q) arm of chromosome 13 at position 14.2 (13q14.2) and encodes an enzyme that plays a significant role in the metabolism of thiopurines. This enzyme is part of the nudix hydrolase superfamily and is responsible for dephosphorylating the active metabolites of thiopurines, namely thioguanosine triphosphate (TGTP) and deoxy-thioguanosine triphosphate (TdGTP). By doing so, it prevents these drugs from being incorporated into cells, thereby reducing their cytotoxic effects and overall efficacy in treatment. Variants in the NUDT15 gene are particularly prevalent among Asian, Hispanic, and Native American populations, and understanding these mutations is essential for optimizing thiopurine therapy and minimizing adverse drug reactions.