The MLH1, IHC without Interpretation test contains 1 test with 2 biomarkers.
Brief Description: The MLH1 Immunohistochemistry (IHC) test is a specialized laboratory test used to detect the presence or absence of the MLH1 protein in tissue samples, typically from a tumor. MLH1 (MutL Homolog 1) is a crucial protein involved in DNA mismatch repair (MMR), a system that corrects errors that occur during DNA replication. Immunohistochemistry utilizes specific antibodies to visualize the expression of proteins in tissue sections under a microscope, providing valuable diagnostic and prognostic information.
This test does not provide Interpretation for MLH-1 Ag result.
Collection Method: Tissue collection
Specimen Type: Formalin-fixed paraffin embedded tissue
Test Preparation: No preparation required
When and Why a MLH1 Immunohistochemistry Test May Be Ordered
A healthcare provider may order an MLH1 IHC test for several reasons:
- Diagnosis of Lynch Syndrome: If a patient has a family or personal history suggestive of Lynch syndrome, a hereditary cancer syndrome associated with a higher risk of colorectal, endometrial, and other cancers.
- Colorectal or Endometrial Cancer Assessment: In cases of colorectal or endometrial cancer, particularly when the patient is young or the tumor has certain histological features, the MLH1 IHC test helps determine the cause of the cancer – whether it's sporadic or hereditary.
- Evaluation of Tumor Characteristics: Understanding the MMR status of a tumor can influence treatment decisions and provide prognostic information.
What the MLH1 Immunohistochemistry Test Checks For
The MLH1 IHC test specifically checks for the presence of the MLH1 protein in the cells of a tissue sample. The absence of staining (indicating the absence of the MLH1 protein) suggests a possible deficiency in the MMR system. This deficiency can lead to microsatellite instability (MSI), a condition where repeated DNA sequences become unstable, which is a hallmark of certain types of cancer, including those associated with Lynch syndrome.
Additional Lab Tests Ordered Alongside the MLH1 Immunohistochemistry Test
When an MLH1 IHC test is ordered, additional tests that may be performed include:
- MSI Testing: To check for microsatellite instability, which is often seen in MMR-deficient tumors.
- Immunohistochemistry for Other MMR Proteins: Such as MSH2, MSH6, and PMS2, to get a comprehensive view of the MMR system.
- Genetic Testing for Lynch Syndrome: Particularly if MLH1 protein is absent, to determine if there is a hereditary basis for the MMR deficiency.
- BRAF Mutation Testing: In colorectal cancer, testing for BRAF V600E mutation can help distinguish between sporadic cancer (often associated with this mutation) and Lynch syndrome-related cancer.
Conditions or Diseases Requiring a MLH1 Immunohistochemistry Test
The MLH1 IHC test is particularly important in the context of:
- Colorectal Cancer: Especially in younger patients or those with a family history suggestive of Lynch syndrome.
- Endometrial Cancer: As Lynch syndrome also increases the risk for this type of cancer.
- Other Cancers Associated with Lynch Syndrome: Including ovarian, gastric, and urinary tract cancers, among others.
Usage of MLH1 Immunohistochemistry Test Results by Health Care Providers
Healthcare providers use the results of the MLH1 IHC test to:
- Diagnose Lynch Syndrome: If MLH1 protein is absent, it may indicate a genetic predisposition to certain types of cancer.
- Guide Treatment Choices: Some treatments may be more effective in tumors with MMR deficiency.
- Inform Prognosis and Surveillance Strategies: Understanding MMR status helps in assessing the prognosis and in planning appropriate surveillance for secondary cancers.
- Facilitate Genetic Counseling: The test results can guide decisions about genetic testing for the patient and potentially affected family members.