hMLH1 Methylation Status


For determining methylation status of hMLH1, a major mismatch repair (MMR) gene, that is responsible for correcting errors in DNA replication and play a major role in gene inactivation in sporadic colorectal cancer with microsatellite instability (MSI). While MSI has been reported in most of patients with hereditary nonpolyposis colorectal cancer (HNPCC) carrying germline mutation of the MMR genes, a substantial proportion of sporadic colorectal cancer cases with no obvious family history also show MSI. This test can be used in determining methylation status of hMLH1 promoter which correlates with the loss of hMLH1 expression.


Bisulfite treatment of DNA followed by PCR amplification of both unmethylated and methylated hMLH1 promoter sequences with products detected by capillary electrophoresis / GeneScan analysis.

Test Parameters

Detection of methylation in a small proximal region of the gene promoter only. Partial methylation may not be detectable due to limitation of the methodology.

Turnaround Time

Eight to 10 working days.

Sample Requirements

10-µm sections of microdissected, paraffin-embedded tissue on five to six slides with separation or indication of normal and tumor areas. Send at room temperature.

Please provide a copy of the corresponding pathology report.

CPT Codes


Additional charges may apply for tissue extraction.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.