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Microsatellite Instability-High (MSI-H)/Mismatch Repair Deficient (dMMR) Cancers

Name of disease:

Microsatellite Instability-High (MSI-H)/Mismatch Repair Deficient (dMMR) Cancers

ICD-10 diagnosis code:



Microsatellite Instability-High (MSI-H)/Mismatch Repair Deficient (dMMR) is the condition of accumulated genetic mutation due to indel mutation and thus loss of function of DNA mismatch repair genes.

Pattern of inheritance:

Most cases are inherited from parents in an autosomal recessive pattern, de novo mutations are rare.


Microsatellite Instability-High (MSI-H)/Mismatch Repair Deficient (dMMR) had prevalence of 14-16% in patients across all tumour types, of which Lynch syndrome-associated tumor types (e.g. endometrial, colon, rectal, gastric) had higher prevelance comparitively.


Molecular genetic tests to screen for MSI-H markers or alterations in mismatch repair genes. Immunohistochemistry to assess mismatch repair protein expression.

Age of onset:

Any age

Common signs and symptoms:

Development of one or more than one type of cancer, including endometrium, colon, gastric, ovarian, urinary tract, hepatobiliary tract, skin, and brain cancers Abnormal growths (polyps) in intestinal tract

Available treatments (medicinal and non-medicinal):

Different types of chemotherapeutic and immunotherapeutic (e.g. Nivolumab, Pembrolizumab) are used depend on the tumor type and biomarkers contained in the tumors. For example, Pembrolizumab are suitable for unresectable or metastatic solid tumors with MSI-H/dMMR characteristics. Nivolumab could be used independently or combined with Ipilimumab.

Disease management tips:

Periodic general check-ups are recommended to track tumor development.