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Beaumont Laboratory

Microsatellite Instability by PCR (MSI)

HNPCC Screen, MSI Testing, SOFT LAB: MMSIG, SOFT GENE: MMSI

Specimen Collection Criteria

Collect: Formalin-fixed, paraffin-embedded tumor block and separate normal tissue block with corresponding H&E slides. Tissue should be well fixed and well processed. Average tissue size 5.0 mm2.

  • DNA will be assessed for quality. If it is deemed unacceptable, testing will be cancelled with client notification.
  • The specimen must be accompanied by a completed requisition and must contain the patient name, date of birth, collection date, ordering physician, and source of specimen.   

Physician Office/Drawsite Specimen Preparation

Maintain paraffin-embedded tissue at room temperature (20-26°C or 68-78.8°F) until transport.

Preparation for Courier Transport

Transport: Paraffin-embedded tissue, at room temperature (20-26°C or 68-78.8°F).

Rejection Criteria

  • Decalcified tissue.
  • Fixatives other than 10% neutral buffered formalin.
  • Improper labeling or inadequate information. 

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Indefinitely
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Room Temperature (20-26°C or 68-78.8°F): 7 days

Laboratory

Royal Oak Clinical Molecular Pathology Laboratory.

Performed

As received.
Results available in 7 days.

Reference Range

Microsatellite instability: 0-9 markers. Microsatellite stable, unstable-low, unstable-high. Results obtained with tumor DNA are compared with results obtained with the patients normal DNA.

Test Methodology

DNA is extracted from the tissue. Primers to six NCI consensus microsatellites are used to amplify both tumor and normal DNA. Fluorescently labeled products are analyzed by capillary electrophoresis. Three additional microsatellite primer sets are used if necessary for clarification of results.

Interpretation

Microsatellite stable, unstable-low, unstable-high.

Clinical Utility

Detects instability of microsatellite loci associated with a loss or suppression of DNA mismatch repair complex.

Clinical Disease

Epiphenomenon or heritable colorectal adenocarcinoma MSI conditions.

CPT Code

81301.

Test Codes

SOFT LAB: MMSIG, SOFT GENE: MMSI

Last Updated

03/14/2017

Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.

This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.