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Arch Pathol Lab Med. 2005 Nov;129(11):1385-9.

Testing for defective DNA mismatch repair in colorectal carcinoma: a practical guide.

Author information

  • 1Mayo Clinic, Rochester, MN, USA. lawrence.burgart@allina.com

Abstract

CONTEXT:

Significant bench and clinical data have been generated during the last decade regarding DNA mismatch repair in colorectal carcinoma.

OBJECTIVES:

To review clinically relevant aspects of defective DNA mismatch repair in colorectal carcinoma and to suggest testing algorithms for identification of these tumors in the sporadic and familial settings.

DATA SOURCES:

This article is based on literature review and clinical testing experience of more than 2000 patient samples.

CONCLUSIONS:

Approximately 15% of colorectal carcinomas arise as a result of defective DNA mismatch repair. Ninety percent of these carcinomas are sporadic, arising as a result of methylation of the MLH1 gene promoter, silencing expression. These sporadic carcinomas have improved stage-specific prognosis and can be identified by demonstrating aberrant loss of expression with an MLH1 immunoperoxidase stain. Familial colorectal carcinomas with defective DNA mismatch repair (Lynch syndrome) are due to a germline defect in one of several DNA mismatch repair genes. The familial carcinomas are best identified with a combination of immunohistochemistry and molecular microsatellite analysis. This testing facilitates subsequent directed genetic testing of the proband and family members.

PMID:
16253016
[PubMed - indexed for MEDLINE]
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