KRAS Codon 146 Mutational Analysis
The KRAS gene is mutated in over 30% of colorectal cancers. The majority (~82%) of reported mutations are in codon 12. Mutations at codons 13 and 61 contribute to a lesser degree, accounting for ~17% and ~1% respectively. Recently, activating mutations involving codon 146 of exon 4 of KRAS have been described with frequencies ranging from 1-4% in colorectal cancers. Rare cases of codon 146 mutations were also found in acute myeloid leukemia and in acute lymphoblastic leukemia cell lines. Mutations in codons 61/146 of KRAS have been shown to predict resistance to EGFR-targeted therapy (cetuximab), especially in patients that are wild-type at codons 12 and 13 in one study. Some studies also report that the frequency of codon 146 mutations is higher than the frequency of mutations in codon 61. The assay detects activating mutations in codon 146 of KRAS.
PCR-based DNA sequencing analysis was performed. The analysis was limited to codons 98 to 150 of the KRAS gene. The presence of mutations outside the tested codon cannot be excluded. The lower limit of detection is approximately one cell bearing the mutation per ten cells (10%).
This assay will detect mutations present in exon 4 of KRAS. The sensitivity of the Sanger sequencing assay is 20% of variant sequence in the background of wild-type sequence.
• 10 ug of purified DNA, sent on dry ice
• Four to six unstained recut slides of formalin-fixed, paraffin embedded tissue containing adequate amounts of tumor to be analyzed (See Sensitivity.)
The area of tumor to be analyzed should be indicated by circling the area on the bottom side of the slide or in a separate H&E-stained guide section.
Please provide a copy of the corresponding pathology report.
Additional charges may apply for tissue extraction.
The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.