Testing method for microsatellite instability of blood ctDNA

Abstract

The invention discloses a testing method for microsatellite instability of blood ctDNA. The method comprises the steps of performing probe capturing on the cfDNA which comprises ctDNA, and establishing a sequencing libray and PGM sequence according to an acquired target product; performing partitioning, quality controlling, filtering and comparing on generated data; then performing microsatelliteloci sequence extraction through a perl program, and comparing with a normal microsatellite sequence, detecting an abrupt change condition of the microsatellite loci and recording the abrupt change type, and finally evaluating the integral microsatellite stability state of the sample according to statistics of the stability of each microsatellite loci. The method can effectively and accurately test the microsatellite instability state of the sample and furthermore can test the abrupt change condition of the microsatellite instability loci. Compared with a traditional PCR testing method, the testing method according to the invention has advantages of higher speed, higher convenience, lower cost and more comprehensive testing.

Description

technical field [0001] The invention belongs to the technical field of biological information, and in particular relates to a method for detecting microsatellite instability of blood ctDNA. Background technique [0002] Microsatellite sequences (Microsatellite, MS) or simple tandem repeats (Simple Sequence Repeat, SSR) widely exist in prokaryotic and eukaryotic genomes, and are composed of 10 to 50 repeating units consisting of 1 to 6 nucleotides in series. Highly polymorphic simple tandem sequences. Microsatellite instability (Microsatellite instability, MSI) is a phenotype of insertion or deletion of base pairs in the microsatellite region due to replication errors. Compared with DNA from normal tissues, DNA sequences with microsatellite instability show shifts in allelic bands, increase in band intensity, or acquire additional band patterns during electrophoresis. The main reason microsatellite instability occurs is likely to be due to abnormal function of pairing error...

AI Technical Summary

Problems solved by technology

However, after the death or apoptosis of normal human cells, some free DNA (cell free DNA, cfDNA) will be released into the blood, because the number of tumor cells in tumor patients is much lower than that of normal cells, and the content of cfDNA in the plasma is very low. However, ctDNA only accounts for 0.1%-5% of cfDNA, and the content of ctDNA in plasma of tumor patients with different cancer types and different courses of disease varies greatly. Therefore, compared with tissue detection, detection of microsatellite instability of ctDNA requires more high sensitivity and specificity

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