MLH1 Methylation

The MLH1 Methylation test contains 1 test with 1 biomarker.

Brief Description: The MLH1 Methylation test is a molecular diagnostic test used to detect abnormal methylation in the MLH1 gene. MLH1 (MutL Homolog 1) is one of the key genes involved in DNA mismatch repair (MMR), a process crucial for maintaining genomic stability. Abnormal methylation of the MLH1 promoter region can lead to gene silencing, disrupting the DNA repair process and increasing the risk of developing certain types of cancers, particularly colorectal cancer.

Collection Method: Blood Draw

Specimen Type: Whole Blood

Test Preparation: No preparation required

When and Why a MLH1 Methylation Test May Be Ordered

This test is commonly ordered in the following contexts:

1. Evaluation of Colorectal Cancer: Particularly when a tumor exhibits microsatellite instability (MSI) or loss of MLH1 protein expression, which are hallmarks of Lynch syndrome but can also be caused by MLH1 methylation.
2. Risk Assessment for Lynch Syndrome: When determining whether colorectal or endometrial cancer is sporadic or associated with Lynch syndrome.
3. Guiding Treatment Decisions: Certain therapies may be more effective in cancers with MLH1 methylation.

What the MLH1 Methylation Test Checks For

The MLH1 Methylation test assesses the methylation status of the promoter region of the MLH1 gene. Methylation is a biochemical process that adds a methyl group to the DNA, often leading to gene silencing. In the case of the MLH1 gene, hypermethylation (an excessive amount of methylation) in its promoter region can inhibit gene expression, leading to a deficiency in the DNA mismatch repair system and increasing the risk of developing cancer.

Additional Lab Tests Ordered Alongside the MLH1 Methylation Test

Alongside an MLH1 Methylation test, other tests may include:

• Microsatellite Instability (MSI) Testing: To determine whether the cancer cells exhibit MSI, a condition often associated with DNA repair defects.
• Immunohistochemistry (IHC) for MMR Proteins: To check for the presence of proteins involved in DNA mismatch repair, including MLH1, MSH2, MSH6, and PMS2.
• Genetic Counseling and Testing for Lynch Syndrome: If the MLH1 methylation is found to be absent, genetic testing for Lynch syndrome may be recommended.

Conditions or Diseases Requiring a MLH1 Methylation Test

The MLH1 Methylation test is primarily used in the context of:

• Colorectal Cancer: Especially in cases where the cancer exhibits characteristics that might be associated with Lynch syndrome or where there is a need to distinguish between sporadic cancer and hereditary cancer syndromes.
• Endometrial Cancer: Since Lynch syndrome can also increase the risk of developing endometrial cancer.

Usage of MLH1 Methylation Test Results by Health Care Providers

Healthcare providers use the results of the MLH1 Methylation test to:

1. Differentiate Between Sporadic and Hereditary Cancer: If MLH1 methylation is detected, the cancer is more likely to be sporadic rather than a result of Lynch syndrome.
2. Inform Treatment Decisions: Some treatments may be more effective in cancers caused by MLH1 methylation.
3. Guide Genetic Counseling: If methylation is not detected, patients may be referred for genetic testing for Lynch syndrome.
4. Risk Assessment for Family Members: Understanding whether a patient’s cancer is due to Lynch syndrome can help assess the risk for family members and guide their surveillance strategies.