The correlation between MSI and tumorigenesis
Microsatellites are short tandem repeat DNA sequences, with a length of 1-6 base pairs. These repeat sequences exist widely in the genome. Under normal conditions, somatic MS DNA mutation frequency is around10-5—10-7. In 1993, Professor Bert Vogelstein discovered a high frequency of microsatellite mutations in hereditary nonpolyposis colorectal cancer cells (compared to normal tissue, microsatellite of tumor tissue has its length changed due to insertions or deletions of repeating units). Studies have shown that microsatellite instability may be an important mechanism of hereditary colorectal cancer occurrence.
Lynch syndrome (also called hereditary nonpolyposis colorectal cancer, HNPCC) is highly correlated with mismatch repair defect (MMR exists in somatic cells and can repair DNA base mismatches). It is an autosomal-dominant disease and accounts for about 5% of all colorectal cancer. Lynch syndrome patients suffer higher risks of colorectal cancer, gastric cancer, endometrial cancer and other kinds of cancer, including an 80% possibility of developing colorectal cancer.
Is one of tumor precision medicine products, applicable for all colorectal cancer patients and other patients who screen for Lynch syndrome (such as endometrial cancer, gastric cancer). MSI testing provides the most accurate evidence for medication in clinical diagnosis, molecular classification and health management, as well as key information for new scientific and clinical discoveries.
All colorectal cancer patients and other patients who undergo screening for Lynch syndrome (such as endometrial cancer, gastric cancer)
Tumor sample (one of the following)
Fresh tissue: surgery (mung bean size), biopsy (> 2 pieces); formalin fixed tissue (1 piece of mung bean size)
Frozen tissue: surgery (mung bean size), biopsy (> 2 pieces)
Paraffin slides: surgery (> 5 slides), biopsy (15-20 slides)
Paraffin blocks: 1 piece (mung bean size)
5 ml peripheral blood, or 2 ml saliva, or 50 ml saliva mouthwash (choose one, peripheral blood preferred)
Turnaround time (TAT)
5 days (upon receiving sample)