Loop-mediated isothermal amplification (LAMP) is a novel nucleic acid amplification method, which amplifies DNA with high specificity, sensitivity, rapidity and efficiency under isothermal conditions using a set of four specially designed primers and a Bst DNA polymerase with strand displacement activity. The basic principle, characteristics, development of LAMP and its applications are summarized in this article.

Objective:To establish a disk (CD) microfluidic chip detection platform for the rapid detection of CALR-1 and CALR-2 mutations in patients with cerebral infarction, and summarize its clinical application value.Methods:Based on microfluidic technology and loop mediated isothermal amplification technology, a CD microfluidic chip detection platform for simultaneous detection of CALR-1 and CALR-2 gene mutations were established, and the sensitivity, specificity, repeatability and accuracy of the platform were verified. A total of 124 patients with cerebral infarction treated in Huashan Hospital, Shanghai Medical College, Fudan University from November 2019 to March 2021 were prospectively selected into the experimental group; and 80 healthy subjects were included in the control group. The CALR-1 and CALR-2 gene mutations in anticoagulant peripheral blood samples were detected by the CD microfluidic chip. Each chip could detect 4 samples at the same time and synchronously detect 3 indexes of each sample. The detection results could be obtained after isothermal amplification for 40 min. At the same time, sequencing method was used to verify the test results, and the consistency of the results of the two detection methods was compared.Results:Using this CD microfluidic chip platform, the synchronous amplification of 3 indexes in the sample could be completed within 40 min without the need of thermal circulation, and the whole detection process of the sample could be completed within 60 min. For samples with a high concentration of target nucleic acid, typical positive signals could be visualized after amplification for 10 min, and the test results would be available within 30 minutes after receiving the samples. The detection sensitivity of CD microfluidic chip method for CALR-1 and CALR-2 mutation load concentration was 1.0% and 0.5% respectively. Nonspecific amplification was not observed for the non-target nucleic acid samples, indicating the high specificity of this method. The coincidence rates of intra and inter batch repeatability were 100% (20/20) respectively. Two samples with CALR gene mutation were found in the cerebral infarction group, both of which were CALR-1 mutations (L367fs*46). There was no CALR-1 or CALR-2 mutation in the control group. The detection results of CD microfluidic chip method were completely consistent with the sequencing verification results (100% [204/204]).Conclusions:The CD microfluidic chip method could be used for the detection of CALR-1 and CALR-2 gene mutations in clinical samples of patients with cerebral infarction. This method has the advantages of high detection sensitivity, good detection specificity, fast detection speed and high detection flux, which is helpful to clarify the etiology of patients with cerebral infarction.