CPT® Code 81318

PMS2 (postmeiotic segregation increased 2 [S. cerevisiae]) (eg, hereditary non-polyposis colorectal cancer, Lynch syndrome) gene analysis; known familial variants

The CPT® Code 81318 pertains to the molecular genetic testing of the PMS2 gene, specifically focusing on known familial variants. This testing is crucial for identifying mutations that increase an individual's risk of developing hereditary non-polyposis colorectal cancer (HNPCC), commonly referred to as Lynch syndrome. The PMS2 gene, located on chromosome 7, plays a vital role in encoding proteins responsible for DNA repair. When mutations occur in this gene, they can lead to the production of an abnormally short or inactive PMS2 protein, which is less effective at repairing DNA. Over time, the accumulation of unrepaired DNA errors can result in the proliferation of cells into tumors, significantly raising the risk of colorectal and other cancers. The specific mutation associated with PMS2 can also lead to a rare variant of Lynch syndrome known as Turcot syndrome, which is characterized by the development of brain tumors, such as glioblastoma, alongside colorectal cancer. It is important to note that some individuals may develop HNPCC 'de novo,' meaning the mutation arises spontaneously in the germ cell or fertilized egg, rather than being inherited from a parent. In contrast to the full sequence analysis performed under CPT® Code 81317, which compares gene segments to identify similarities and relationships, CPT® Code 81318 focuses on testing for known familial variants. This is particularly beneficial for family members of individuals diagnosed with PMS2 mutations, as it can help identify common variants and assess the risk factors for relatives who may share the same genetic mutation. Additionally, CPT® Code 81319 addresses the testing for PMS2 duplication or deletion variants, which are critical for understanding the genetic landscape of the PMS2 gene. Overall, the testing under CPT® Code 81318 is an essential tool in the early detection and management of hereditary cancer risks associated with PMS2 mutations.