From Disease Diagnosis to Personalized Medicine: The Clinical Applications of ddPCR Gene Expression

ddPCR gene expression

Today, scientists have a broad spectrum of bioanalytical tools such as PCR, LC-MS, **MSD cytokine assay**, etc. However, when it comes to gene expression and copy number analysis, PCR assays, particularly digital PCR analysis, have been leading the way. Droplet digital PCR is a technique that is established on water-oil emulsion droplet technology. This tool divides the sample into 20000 droplets, where each droplet acts as a PCR reaction. Besides, ddPCR assays use similar reagents and workflows to standard qPCR assay development.

ddPCR system water oil emulsion droplets partition and separate the template DNA molecules. Essentially, each droplet functions as an individual well or test tube, making the sample partitioning step a crucial aspect of the ddPCR technique. Hence, ddPCR assays are increasingly used for gene expression analysis and nucleic acid assessments. ddPCR technique divides nucleic acid samples into nanolitre-sized droplets where PCR amplification happens within each droplet. Therefore, this technique requires smaller volumes of samples and reagents, making it more cost-effective.

The current article discusses the advantages of the ddPCR system over traditional PCR techniques and dives into the applications of **ddPCR gene expression** analysis.

ddPCR gene expression

qPCR CRO and laboratories employ ddPCR systems as they offer enhanced performance compared to traditional PCR techniques by providing a scalable and practical tool for gene expression analysis. Traditional serial sample dilution is laborious and causes pipetting errors, while chip-based methods use complex fluidics schemes to partition the sample. ddPCR assays overcome all these limitations by partitioning the sample into a liquid phase and a single step. Besides, thousands of droplets mean a single sample volume generates thousands of data points. Additionally, automated ddPCR systems systemize the workflow for droplet generation, cycling droplet reading, and analysis.

The enhanced precision of ddPCR assays offers higher resolution for gene expression analysis. This precision helps researchers identify and quantify finer fluctuations in expression levels while providing greater sensitivity to quantify RNA or rare targets in limited sample volumes. Besides, ddPCR gene expression analysis is employed at DNA and RNA levels in different areas, including:

• Detecting and measuring genomic DNA methylation
• Highly sensitive transcriptional analysis coupled with absolute quantification
• Identifying rare mRNAs and miRNAs

Gene expression regulation at the genomic level depends on the methylation of genomic DNA and the interactions between DNA histone proteins, which are influenced by several histone modifications such as acetylation, phosphorylation, and methylation. Methylation of genomic DNA usually takes place at CpG islands in the non-coding region and usually reduces gene expressions.

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PCR is one of the common techniques employed to study DNA methylation. This method employs primer pairs that can differentiate between methylated and unmethylated CpG Islands. Due to its enhanced sensitivity and capacity to differentiate alleles, ddPCR assays provide more accurate and sensitive measurements of DNA methylation. Besides, its precision in operating with low amounts of study samples makes it ideal for experiments such as chromatin immunoprecipitation. In conclusion, ddPCR systems are critical for copy number variation and gene expression analysis.