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Microsatellite Instability by PCR
|Utilization Guidelines||Criteria for HNPCC testing (revised Bethesda guidelines):
1. Colorectal cancer diagnosed in a patient who is less than 50 years of age.
2. Presence of synchronous, metachronous colorectal, or other HNPCC-associated tumors, regardless of age. HNPCC-associated tumors include colorectal, endometrial, stomach, ovarian, pancreas, ureter and renal pelvis, biliary tract, and brain (usually glioblastoma as seen in Turcot syndrome) tumors; sebaceous gland adenomas and keratoacanthomas in Muir-Torre syndrome; and small bowel carcinoma.
3. Colorectal cancer with the MSI-H histology diagnosed in a patient who is less than 60 years of age. Note that inclusion of the age criteria is controversial.
4. Colorectal cancer in a patient with one or more first-degree relatives with an HNPCC-related tumor, with one of the cancers being diagnosed under age 50 years.
5. Colorectal cancer in a patient with two or more first- or second-degree relatives with HNPCC-related tumors, regardless of age.
UCSF Clinical criteria for HNPCC testing in gynecologic tumors:
Nearly half of women with HNPCC will present with a gynecologic tumor, rather than a colon cancer.
1. Endometrioid histology at any GYN location in a patient under 50 in a definitive surgical procedure (i.e., not just biopsy, wait for primary surgery).
2. Any adenocarcinoma at any GYN location in a patient with colon cancer.
3. Clinician suspicion for Lynch syndrome.
Note: BRAF V600E Mutation testing may be performed on samples that are MSI-High and show loss of MLH1 by immunohistochemistry to distinguish the sporadic MSI-high cases (BRAF mutation positive) vs. the MSI-high cases associated with Lynch syndrome (BRAF mutation negative
|Performed by||Molecular Diagnostics|
|In House Availability||Run 1x per week, DNA extraction started on Monday, day shift only|
|Method||Multiplex PCR with analysis by capillary electrophoresis|
|Collection Instructions||Testing should be ordered only on surgical excision samples. Biopsy material is not appropriate.
Blocks selected for MSI PCR testing must contain both tumor and normal tissue. If only tumor is present on the block, select an additional block with normal tissue
Areas of tumor must contain at least 50% tumor cells. The lab can remove adjacent non-tumor tissue, so the entire slide does not need 50% tumor cells, just the area with tumor.
Label slides with pathology case number and block identification.
For UCSF Samples (from remote sites) Click here for sample collection instructions
For NON-UCSF Samples Click here for Requisition form & Account set-up instructions. Note we only do institutional billing.
|Sample type||Formalin-fixed, paraffin-embedded 10 micron tissue sections on five (5) unstained, uncharged glass slides. One adjacent H&E stained slide should be included.|
|UCSF Rejection Criteria||All required slides not included. Insufficient tumor or normal tissue present on slide as determined by pathologist. Slides not labeled or not accompanied by completed requisition form (if not ordered directly through Department of Pathology).|
|Processing notes||Send samples on next day shift courier run to China Basin Molecular Diagnostics Lab.|
|Units||Number of microsatellite loci showing instability out of five tested|
|Synonyms||MSI; HNPCC testing; Hereditary non-polyposis Colon cancer; Hereditary non-polyposis Colorectal cancer|
|Stability||Formalin-fixed, paraffin-embedded tissues are stable indefinitely at room temperature|
|Turn around times||10-14 days|
|Additional information||This test is typically run in conjunction with immunohistochemical staining for mismatch repair proteins, performed by the UCSF Pathology Laboratory. Microsatellite Instability by PCR may also be ordered as a separate test.
Microsatellite Instability by PCR is designed to aid in the identification of patients who harbor germline mutations in mismatch repair (MMR) proteins that are associated with HNPCC. It is important to note that defective MMR resulting in MSI can also arise spontaneously in a tumor (i.e., without inheritance of a mutant MMR gene), and therefore the presence of MSI is not pathognomonic for HNPCC.
Results from this test should be correlated with the patient's clinical presentation, family history and any findings from immunohistochemical staining for mismatch repair proteins in the tumor. Genetic counseling may be recommended for some cases.
BRAF V600E Mutation testing may be performed on samples that are MSI-High and show loss of MLH1 by immunohistochemistry to distinguish the sporadic MSI-high cases (BRAF mutation positive) vs. the MSI-high cases associated with Lynch syndrome (BRAF mutation negative.
The test was validated by UCSF Clinical Laboratories to confirm performance characteristics, in compliance with current guidelines for clinical implementation
|LDT or Mod FDA?||Yes|
|Last Updated||3/13/2013 8:57:05 AM|
If you have additional questions regarding this test, please call: 415-353-1667