CPT® Code 81273

The CPT® Code 81273 pertains to molecular genetic testing specifically aimed at identifying the D816 variant(s) mutation of the KIT (v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog) gene located on chromosome 4. The KIT gene is crucial as it encodes a protein that is part of the receptor tyrosine kinase family, which plays a significant role in signal transduction. This process involves the transmission of signals from the cell surface into the interior of the cell, facilitating various cellular functions. The D816 variant is characterized by a somatic A to T missense mutation at position 2447 of the coding sequence, leading to a critical substitution of aspartate (D) with valine (V) at position 816 within the kinase domain. This mutation results in the autoactivation of the KIT receptor tyrosine kinase, which can lead to the development of mastocytosis. Mastocytosis is a condition marked by the excessive production of mast cells, which can manifest in two primary forms: cutaneous mastocytosis, affecting the skin, and systemic mastocytosis, impacting internal organs. In cutaneous mastocytosis, often seen in children, mast cells accumulate in the skin, leading to symptoms such as flushing and itching. Conversely, systemic mastocytosis primarily affects adults and involves the accumulation of mast cells in organs such as the liver, spleen, bone marrow, and small intestine, resulting in a range of symptoms including flushing, itching, abdominal cramps, musculoskeletal pain, hypotension, and potentially life-threatening anaphylaxis. To perform this genetic analysis, blood, bone marrow, or skin samples are collected, typically through procedures such as venipuncture, bone marrow aspiration, or biopsy. The samples are then analyzed for the presence of D816 variant(s) mutation using an allele-specific real-time polymerase chain reaction assay.