MSH2 Microsatellite Instability
Companion Diagnostic
MSH2 Microsatellite Instability is an FDA-approved companion diagnostic used to help identify patients who may be eligible for targeted therapies.
Use
MutS Homologue 2 (MSH2) is a mismatch repair (MMR) protein and its deficiencies result in microsatellite instability (MSI) in cancers such as colorectal and endometrial. This test is significant for evaluating the presence of microsatellite instability which is associated with malignancies and can guide therapeutic decisions, especially in relation to the FDA-approved companion diagnostic for venting MMR RxDx use.
Special Instructions
Special considerations for specimen handling include that fresh tissues may be fixed in formalin for 24-72 hours by collection sites and then transferred to 70% ethanol for longer term storage if necessary. Positively charged glass slides are mandated to prevent background staining and loss of tissue.
Limitations
Specimens must be fixed in 10% neutral buffered formalin (NBF) or B plus; all other fixatives will be rejected. Unstained slides must be left unbaked and on positively charged glass slides. The test uses immunohistochemistry methodology, limiting it to protein expression evaluation, not suitable for genetic mutation analysis. The fresh tissue stability limits are a maximum of 72 hours, so prolonged delays in testing can affect results.
FDA ApprovedCompanion Diagnostic
Methodology
Immunoassay (IHC)
Biomarkers
Result Turnaround Time
2 days
Related Documents
For more information, please review the documents below
Specimen
Tissue (Fixed (Non-FFPE))
Volume
Not provided
Minimum Volume
Not provided
Collection Instructions
Fixative should be at a 20:1 fixative to tissue ratio, 10% neutral buffered formalin for 6-72 hours (48-72 hours PREFERRED). Specimens may be transferred to 70% alcohol for transport after fixation.
Storage Instructions
Store at 15°C to 25°C.
Causes for Rejection
Specimens must be fixed in 10% NBF or B plus. All other fixatives will be rejected.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | ≤ 72 Hours |