Single nucleotide polymorphism( SNP) is a major source of genetic differences, and the number of SNP is extremely large. Consequently, a high-throughput, rapid and cost-effective technique is essential for SNP typing. Recently, a set of solutions aimed directly at the bottlenecks in SNP detection were put forward, which including direct PCR from human whole blood, adapter-ligation mediated allele-specific amplification, gene polymorphism detection in one tube, microplate array parallel gel electrophoresis and microchip electrophoresis. These methods have been successfully applied in pharmacogenomics, disease-related research, herbal medicine identification and quality control. The results showed that the advantages of the genotyping platforms are highly specific, sensitive, easy to operate and inexpensive with a good prospect of application. The principles and applications of the genotyping platforms in detail were described in this paper.

To establish a simple and rapid method to genotype the human single nucleotide polymorphisms(SNPs). Methods:In the presence of the appropriate Cy5-ddNTPs and dNTPs,the primer was extended by one or more bases depending on the sequence at the polymorphic site. The microchip electrophoresis was used to detect the product of extension.The switching characteristics of the primer extension reaction was increased by introducing an artificially mismatched base into the third position from the 3'-terminus of the primers. Results:Three human SNPs were detected and the alleles were distinguished on the basis of size of the extended product. All samples were accurately assayed within 100 s in microchip electrophoresis. Conclusion:This technique offers a high-speed,easy and cheap method for genotyping SNPs.

Proteins presence and differences of the expression level can clarify the physiological or pathological changes in organisms;so the quantitative detection of proteins is vital for disease mechanism research;diagnosis and prognosis evaluation.Traditional protein quantitation methods at the tissue level reflected the average protein expression in cells;but ignore the differences between individual cells.In contrast;approaches for quantitative detection at single-cell level can better reflect the differences.Recently;a number of approaches for such detec-tion have been proposed;including microfluidics;microwell-based technology;optical fiber nanobiosensor;activity-based probe technology and mass spectrometry.The principles;advantages and drawbacks of these approaches are briefly introduced in this review.

Ahigh-resolutionmethodforhumanleukocyteantigen-B(HLA-B)genotypingwasestablished based on the optimized polymerase chain reaction, cloning and sequencing technology. The exon2 and exon3 of HLA-B gene were amplified with primers based on the HLA-B gene sequence. These produced heterozygous alleles were effectively cloned into plasmid DNA based on the principle of plasmid incompatibility, and were followed by bacterial culture. Then Sanger sequencing was carried out and after analyzing the result by software ClustalX2 and IMTG/HLA database comparison, the HLA-B genotype of the samples was achieved. Seven clinical samples were detected, and the results were consistent with those of PCR-SBT genotyping method. The method was cost-effective, high-resolution and it did not require technical software. The use of universal primers simplified the cumbersome design and optimization process of specific primers.

A method for the real-time polymerase chain reaction ( PCR ) coupled with high specific invader assay to detect single nucleotide polymorphism ( SNP) was established. To reduce the background signal, the amount of flap endonuclease 1 ( FEN1 enzyme ) and wild-type detection probe was optimized. Under the optimum conditions including 0. 05 μmo/L invasive oligonucleotide probe, 0. 125 μmol/L wild-type detection probe, 0. 5 μmol/L mutation detection probe, 0. 25 μmol/L each fluorescence resonance energy transfer (FRET) probe and 1. 5 U FEN1, the background signal of wild-type sample and mutation sample was dramatically decreased and the background interference to the detecting results was thus eliminated. A total of 21 cases of aldehyde dehydrogenase-2*2 ( ALDH2*2 ) , 19 cases of cytochrome p450 2 C19*2 ( CYP2 C19*2 ) and 19 cases of CYP2C19*3 were analyzed with the established method, and the genotypes of ALDH2*2 were 10 cases of GG homozygote, 8 cases of GA heterozygote and 3 cases of AA homozygote; the genotypes of CYP2C19*2 were 9 cases of GG homozygote, 8 cases of GA heterozygote and 2 cases of AA homozygote;and the genotypes of CYP2C19*3 were 18 cases of GG homozygote and 1 case of GA heterozygote. These results were consistent with those by pyrosequencing. The established method was specific, simple, short time-consuming and low cost, and could be used for the detection of SNP genotyping with non-polluting in single closed tube.

Objective The NDRG4 gene methylation in stool is a candidate biomarker for non?invasive diagnosis of colorectal cancer. However, the traditional methods for methylation detection could not be well applied to stool samples due to the low sensitivity and low specificity. The aim of this study was to develop a highly sensitive and specific method for quantifying the methylated NDRG4 gene in stools. Methods Forty one stool samples were collected from 12 colorectal cancer patients, 4 adenoma patients and 25 nor?mal persons. The invasive reaction was combined with real?time PCR and the relative quantification was performed by 2-ΔCT method to develop the highly sensitive and specific methylated DNA detection method, which was used for detecting NDRG4 methylation levels in 41 of stool samples. Results The sensitivity of the method was as low as 10 copies of methylated NDRG4 gene fragments. The specificity was high enough to distinguish 0.01% of methylated fragments from un?methylated fragments and 105 copies of unmethylated NDRG4 fragments gave noamplification signals. The detection results from 41 of stool samples showed that detection rate of the NDRG4 gene in stool from adenoma and colorectal cancer groups had a significant difference comparing to that from the normal group. Conclusion The 2-ΔCT method could accurately quantify the methylation levels of the NDRG4 gene in stool samples, and provide an efficient tool for non?invasive colorectal cancer detection.

Pyrosequencing is one of the important genetic polymorphism detection methods currently, but the complicated pretreatment procedure limits its application in clinical test. To simplify the whole process of pyrosequencing, on the basis of the linear_after_the_exponential_polymerase chain reaction ( LATE_PCR) , we improved the primer design method of LATE_PCR, increased the length and the concentration of the excess primer, applied direct amplification technology with whole blood, and established a whole blood_imLATE_PCR method based on common rTaq polymerase and “HpH Buffer” ( High pH buffer ) . The amplification system was optimized, and the influences of blood anticoagulant and the amount of whole blood template were investigated. The single stranded template for the pyrosequencing was obtained by PCR amplification using a single tube in one_step process, and the alcohol dehydrogenase gene polymorphisms of 24 clinical blood samples were then detected successfully. The results could be used to guide clinical individualized medication. The genotypes of ADH1B locus of 24 samples were 6 cases of AA homozygote, 14 cases of AG heterozygote, and 4 cases of GG homozygote. The genotypes of ADH1C were 20 cases of GG homozygote, 4 cases of AG heterozygote, and no cases of AA homozygote.

There are significant individual differences in the antiplatelet effects of aspirin.Three single nucleotide polymorphisms (SNPs),rs5918,rs12041331 and rs730012,are reported to significantly correlate with the efficacy and side effects of aspirin.In the present study,the genotyping method of the three SNPs was established based on the combination of polymerase chain reaction and pyrosequencing technology.Amplification and sequencing primers were designed independently;the amplification conditions were optimized to amplify the three SNPs in the same condition.The sensitivity of the method was detected using original genome DNA at different concentrations.In order to testify the accuracy of the method,the proposed method and Sanger sequencing technology were both used to genotype the three SNPs in 20 blood samples.The results demonstrated that the genotyping method of aspirin-related SNPs was successfully established,with the detection limit being as low as 0.4 ng genome DNA.The genotype results of 20 samples by the proposed method were exactly the same as that of Sanger sequencing.It is evident that the proposed method is sensitive and accurate.

The corona virus disease 2019 (COVID-19) caused by the new coronavirus (SARS-CoV-2) has spread rapidly around the world,posing a serious threat to the public"s health. As of September 30,2020,the number of infected people in the world has reached 33 million,causing more than 1 million deaths. Normalized nucleic acid detection methods based on lab have long turnaround time and high cost. Therefore,there is an urgent need to develop a convenient method to detect SARS-CoV-2,so as to achieve rapid testing and timely control of the epidemic when resources are limited.This review summarizes the point-of-care testing (POCT) methods developed for SARS-CoV-2 in terms of extraction,amplification and detection,and briefly introduces commercial POCT instruments that integrate these three steps,in order to provide references for emergency response and rapid deployment of COVID-19 and other emerging infectious diseases.

Gene editing tools with nucleases as the main component have now implemented programmable targeted mutagenesis or insertion or deletion of mammalian genomes.From zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), CRISPR/Cas system to safer and more accurate Cas9 fusion protein gene editing tools and other nuclease gene editing tools, this paper systematically describes the development and evolution of gene editing, with detailed introduction to the development and optimization of next-generation gene editing tools, and a prospect of the clinical application of and challenges for gene editing tools.