A diagnosis of Lynch syndrome is applied to people with a germline DNA mutation in one of the MMR genes (MLH1, MSH2, MSH6, and PMS2) or the EPCAM gene, identified by genetic testing. Candidates for germline genetic testing can be identified by clinical criteria such as the Amsterdam Clinical Criteria and Bethesda Guidelines, or through tumor analysis by immunohistochemistry(IHC), or microsatellite instability (MSI) testing. In the USA, professional societies recommend testing every colon<unk>  for MSI or IHC as screening for Lynch syndrome, but this is not always performed because of cost and resource limitations. Genetic testing is commercially available and consists of a blood test. Immunohistochemistry Immunohistochemistry (IHC) is a method that can be used to detect abnormal mismatch repair (MMR) protein expression in tumours that are associated with Lynch syndrome. While it is not diagnostic of a Lynch syndrome, it can play a role in identifying people who should have germline testing. Two methods of implementation of IHC testing includes age-based testing and universal testing for all people. Currently, there is no widespread agreement regarding which screening method should be used. Age-based testing for IHC has been suggested in part due to cost-benefit analyses, whereas universal testing for all people with<unk><unk>  ensures people with Lynch Syndrome are not missed. To address the costs, researchers are trying to predict MSI or IHC directly from the way the tumor looks under the microscope, without doing any molecular testing. Microsatellite Instability Mutations in DNA mismatch repair systems can lead to difficulty transmitting regions within the DNA which contain repeating patterns of two or three nucleotides (microsatellites), otherwise known as microsatellite instability (MSI). MSI is identified through DNA extraction from both a tumor tissue sample and a normal tissue sample followed by PCR analysis of microsatellite regions. MSI analysis can be used to identify people who may have Lynch syndrome and direct them for further testing. Classification Three major groups of MSI-H (microsatellite instability – MSI)<unk> s can be recognized by histopathological criteria: * right-sided poorly differentiated<unk> s * right-sided mucinous<unk> s * adenocarcinomas in any location showing any measurable level of intraepithelial lymphocyte (TIL) The histopathological criteria are not sensitive enough to detect MSI from histology but researchers are trying to use artificial intelligence to predict MSI from histology. In addition,<unk>  can be divided into Lynch syndrome I (familial colon<unk>  and Lynch syndrome II<unk>  associated with other<unk> s of the gastrointestinal tract or reproductive system).
Hereditary nonpolyposis colorectal cancer
Familial adenomatous polyposis
MUTYH-associated polyposis
Serrated polyposis syndrome
Hereditary diffuse gastric cancer
Juvenile polyposis syndrome
Attenuated familial adenomatous polyposis
Peutz–Jeghers syndrome