MLH1

Alias/Synonym: DNA Mismatch Repair Protein, MutL Homolog 1

CPT Code: 88342

Includes:

Specimen Type, Preferred:

Formalin fixed paraffin embedded tissue

Specimen Type, Alternate:

Sample Quantity, Preferred:

1 block

2 slides

Sample Quantity, Minimum:

N/A

Transport Container:

Paraffin block

Unstained slides

Transport Temperature:

Room temperature

Collection Instructions:

Block and slide identifiers should be clearly written and match exactly with the specimen ID and specimen labeling as noted on the requisition.

Slides should be positively charged and cut at 3-4 microns for each stain/antibody ordered.

Specimen Stability:

N/A

Rejection Criteria:

No liquid specimens.

Uncharged slides

Clinical Significance:

MLH-1 [G168-15] recognizes human and mouse MLH-1 (80-85 kDa). MLH-1 is involved in the DNA mismatch repair (MMR) process. Loss of a DNA mismatch repair protein can lead to an accumulation of DNA replication errors in the proliferating cells, particularly in areas of short repetitive nucleotide sequences (microsatellite instability). These defects in MMR have been related to human carcinogenesis. Immunostaining for MLH-1 may be useful to aid in identifying the most probable gene responsible for the MSI. Loss of MLH-1 expression may indicate either an inheritable germline defect (e.g. Lynch syndrome) or promoter methylation of the MLH-1 gene, which usually correlates with positive BRAF V600e mutation. Because the MLH-1 protein associates with the PMS-2 protein at the cell surface, loss of MLH-1 often results in destabilization of the PMS-2 protein, resulting in loss of immunohistochemical expression of both proteins. Studies have shown that the expression level of MLH-1 may be a survival indicator.

Limitations:

Turnaround Time:

1 day(s)

Reference Ranges:

N/A

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