Microsatellite instability

No of

Lab method: Fragment analysis

TAT: 3 weeks

Specimen requirements: Paraffin-embedded, formalin-fixed block of tumor tissue from colon and normal tissue

  • The best material of tumor tissue is pre-treatment biopsy.
  • The best material of normal tissue is surgical resection or 2-4 ml of blood (with anticoagulant EDTA).
  • Storage and transport temperature for paraffin-embedded, formalin-fixed tissue blocks is 20-25°C.
  • Testing results cannot be guaranteed when DNA quality is poor or DNA is too fragmented due to previous tissue fixation process.

Ordering information: Go to online ordering or download sample submission form

Indications for genetic testing:

    1. Testing of individuals with colorectal or other Lynch-associated cancers to estimate the probability of mutations in mismatch repair genes
    2. Determination of disease prognosis
    3. Genetic counseling

Microsatellite instability (MSI) is the mutational signature found in colorectal cancers that evolve as a result of inactivation of the DNA mismatch repair system. Defects in the genes involved in mismatch repair lead to an accumulation of somatic mutations in a cell, which may result in the cell becoming malignant. Germline mutations in mismatch repair genes are associated with developing hereditary non-polyposis colon cancer. Approximately 90% of colon cancers from families meeting Amsterdam criteria have MSI.