Lynch Syndrome is an inherited disorder and many a times it is not diagnosed due to various factors such as misdiagnosis. The diagnostic methods are used to identify the Lynch syndrome in patients who are having colorectal cancer and their close relatives. Most of the methods include the mutation analysis and evaluation of the family history of patient.
What Is The Test For Lynch Syndrome?
Various diagnostic methods are used to identify the presence of Lynch syndrome in a particular patient. These testing methods may be used either after the development of tumor or during the screening of a patient having a close relative with cancer due to Lynch syndrome. As Lynch syndrome is an inherited disease, the close relative of a patient should be thoroughly screened. Following are the diagnostic procedures used to identify the Lynch Syndrome.
Various tests are used to reveal whether the cause of the tumor is a gene mutation linked with the Lynch syndrome. The methods include the Immunochemistry analysis and Microsatellite Instability testing. All the cells in the body have the genetic mutation related to Lynch Syndrome. The sample is collected from the tumor of colorectal region or from other organs for further testing.
It has been mentioned that the Lynch syndrome is associated with the mutation in the gene and this is a dominant character. Thus, the person having his parents affected with lynch syndrome have higher chances of developing Lynch syndrome and is at high risk of developing cancer. Thus, the diagnosis is done on the basis of family history.
However, this might lead to misdiagnosis as if a liver cancer metastasized from a colon cancer is not properly linked to colon cancer then there might be chances of misinformation leading to faulty conclusion.
Genetic Counseling and Testing
Genetic testing is done in the patient who have developed cancer and also of the close relative of the patient. The blood is taken from the person and is analyzed for the presence of mutation related to Lynch Syndrome. A positive result indicates the high risk of developing cancer due to Lynch Syndrome while a negative result indicates the absence of any mutation. Initially, the mutation search is conducted with the blood of the patient and later on, predictive search is conducted on other family members.
Type Of Genes Affected
Once the Lynch Syndrome is diagnosed, the next step is to identify which gene is affected. The type of gene affected will give a clear picture regarding the risk for particular type of cancer/s. Various genes involved are MLH1, MSH2 and MSH6. The type of risk may help in taking the precautionary steps.
Once the family members, who are not having cancer, are diagnosed, a screening schedule is maintained for them. The screening schedule would be on the basis of risk of developing particular type of cancer. These techniques include colonoscopy, endoscopy and pelvic examination at regular intervals.
Microsatellite Instability Testing (MSI)
In the MSI testing, the changes in the sequence of DNA in cancer cells are compared with the DNA sequences in non-cancerous cells. This is identified through DNA MMR machine and the changes are read at the similar microsatellite loci.
The immunological staining is done for the four proteins involved in the lynched syndrome. There are antibodies present for these proteins. Any absent staining for these proteins determines the type of mutation occurred.
MLH1 methylation and BRAF methods are the methods used for the diagnosis of mutation due to Lynch syndrome.
Various diagnostic methods are used for the analysis of Lynch syndrome. These methods are implemented either on the patients with colorectal cancer or on the patients having high risk of developing Lynch syndrome. The therapeutic as well as prophylactic treatment is done on the basis of the diagnosis. Further, type of mutation also plays an important role in concluding the type of cancer which can occur in the patients with Lynch syndrome.
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