PMS2

Sequential sections of a colon crypt showing normal high expression of PMS2 (A), ERCC1 (B) and ERCC4 (C)

PMS2 (Postmeiotic Segregation Increased 2) is a gene that encodes one of the several proteins involved in the DNA mismatch repair (MMR) pathway, a critical system for maintaining genetic integrity. The PMS2 protein plays a vital role in correcting DNA replication errors, which, if left unrepaired, can lead to genetic mutations that contribute to the development of various types of cancer, including colorectal cancer, endometrial cancer, and others.

Function

The primary function of PMS2 within the DNA mismatch repair system is to form a heterodimer with another MMR protein, MLH1. This complex, MLH1-PMS2 (also known as MutLα), is essential for identifying and initiating the repair of base-base mismatches and insertion-deletion loops that arise during DNA replication. The MMR system's ability to correct these errors is crucial for preventing the accumulation of mutations and maintaining genomic stability.

Genetic and Clinical Significance

Mutations in the PMS2 gene are associated with Lynch syndrome (also known as Hereditary Nonpolyposis Colorectal Cancer or HNPCC), an inherited condition that significantly increases the risk of developing colorectal cancer and other types of cancer at a younger age than the general population. Individuals with Lynch syndrome may also have an increased risk of cancers of the ovary, stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, and skin.

Testing for mutations in PMS2 and other MMR genes is a critical component of the diagnostic process for Lynch syndrome. Identification of a mutation can lead to increased surveillance and preventive measures for affected individuals and their families.

Genetic Testing and Counseling

Given the implications of PMS2 mutations for cancer risk, genetic testing for these mutations is an important tool for identifying individuals at risk for Lynch syndrome. Genetic counseling is recommended for individuals who have a family history of cancers associated with Lynch syndrome or who are found to have mutations in the PMS2 gene. Counseling can provide information on the risks, benefits, and limitations of genetic testing, as well as guidance on preventive measures and management strategies for those with a positive test result.

See Also

• DNA mismatch repair
• Lynch syndrome
• Colorectal cancer
• Genetic testing
• Genetic counseling