CPT® Code 81315

PML/RARalpha, (t(15;17)), (promyelocytic leukemia/retinoic acid receptor alpha) (eg, promyelocytic leukemia) translocation analysis; common breakpoints (eg, intron 3 and intron 6), qualitative or quantitative

The CPT® Code 81315 pertains to the molecular genetic testing aimed at identifying a specific genetic mutation involving the PML (promyelocytic leukemia) gene and the RARalpha (retinoic acid receptor alpha) gene. This mutation results in a chimeric fusion of the two genes, which is significant in the context of acute myeloid leukemia (AML). In approximately 99% of individuals diagnosed with AML, a translocation occurs between chromosome 15, where the PML gene is located, and chromosome 17, which houses the RARA gene. This translocation leads to the formation of a transcript isoform that can vary in length, categorized as either short or long, depending on the specific breakpoint within the PML gene. The analysis performed under CPT® Code 81315 focuses on common breakpoints, specifically those found in intron 3 and intron 6 of the PML gene. The testing can be qualitative or quantitative, achieved through the extraction of RNA and the application of reverse transcription-polymerase chain reaction (RT-PCR) to examine the PML/RARA fusion transcripts. A control sample from the ABL gene is also amplified to ensure the quality of the test and to facilitate relative quantification of the results, which are reported as either positive or negative. In cases where the test yields a positive result, the report will include details about the length of the isoform and the ratio of the target PML/RARA mRNA to the control ABL mRNA. This information is crucial for monitoring the effectiveness of therapy, assessing minimal residual disease (MRD), and predicting the potential for early relapse. The identification of common breakpoints is particularly relevant, as it has been observed that the frequency of these breakpoints can vary by ethnicity, with certain populations exhibiting a higher prevalence of specific breakpoints. Overall, CPT® Code 81315 plays a vital role in the diagnosis and management of acute promyelocytic leukemia (APL) through the detailed analysis of genetic translocations.