CPT® Code 81275

The CPT® Code 81275 pertains to the molecular genetic testing of the KRAS gene, specifically focusing on variants located in exon 2, which includes codons 12 and 13. The KRAS gene is crucial as it encodes the K-Ras protein, a key player in cellular processes such as growth, division, maturation, and differentiation. This protein functions as a molecular switch, toggling between an active state when bound to guanosine triphosphate (GTP) and an inactive state when it hydrolyzes GTP to guanosine diphosphate (GDP). In the presence of specific mutations, a single alteration in the amino acid sequence can lead to continuous activation of the K-Ras protein, resulting in uncontrolled cell proliferation. The KRAS gene is classified within the Ras family of oncogenes and is located on chromosome 12. Mutations in this gene can lead to various disorders, including an atypical form of Noonan syndrome, characterized by symptoms such as intellectual disability, short stature, congenital heart defects, and skeletal anomalies. Additionally, the KRAS gene is implicated in cardiofaciocutaneous (CFC) syndrome, which presents with low intellectual function, distinctive facial features, short stature, macrocephaly, and sparse hair. Furthermore, somatic mutations of the KRAS gene are frequently observed in several malignancies, including lung, pancreatic, and colorectal cancers. Notably, mutations at codon 61, which result in a change in the amino acid glutamine, are associated with lung and colorectal cancers, while mutations at codon 146 are primarily found in colorectal cancers and occasionally in acute myeloid leukemia and acute lymphoblastic leukemia. These mutations are also significant as they can predict resistance to EGFR-targeted therapies, such as cetuximab. The testing for these mutations is typically conducted using blood or tissue samples through polymerase chain reaction-based Sanger sequencing of DNA, making it a vital tool in the diagnosis and management of related syndromes and cancers.