Test Name: KRAS Exon 4 Mutation Analysis 


Methodology: Molecular Genetics


Test Description

Bi-directional sequencing of exon 4 of the KRAS gene corresponding to amino acids R97 through Q150. Codon 117 and 146 mutations are detected. For solid tumors, tumor enrichment is performed before extraction. This test may be ordered separately or by reflex after standard KRAS Mutation Analysis. 


Specimen Requirements

•FFPE tissue: Paraffin block is preferred. Alternatively, send 1 H&E slide plus 5-10 unstained slides cut at 5 or more microns. Please use positively-charged slides and 10% NBF fixative. Do not use zinc fixatives.
•Fine needle aspirate (FNA): Requisition must note specimen is FNA. Fresh cells in suspension, unstained air-dried smears (approx. 6-8 slides), or FFPE cell blocks are acceptable if pathologist attaches note verifying sample has >30% tumor or abnormal cells (required). Minimum 10^6 cells.


Storage and Transport

Use cold pack for transport, making sure cold pack is not in direct contact with specimen. Slides can be packed at room temperature.  


Specimen Rejection Criteria

Click here to reference the specimen rejection criteria.


Turn Around Time (TAT): 7 Days


CPT Codes*: 81479


*The CPT codes provided with our Test Descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.