NGS (or next generation sequencing) is a DNA sequencing technology that has revolutionised genomic research. In fact, NGS is now being used in several different fields of life sciences including oncology, life sciences, evolutionary biology, medicine, and forensic science. (COVID-19 sequencing)
Compared to previous sequencing techniques, NGS is highly scalable, enabling sequencing of the complete genome of concern at once. This is known as massive parallel sequencing. If you want to know more about NGS then keep reading below. We will talk in more detail about what NGS is, how it is performed, and what the advantages and disadvantages of using it are:
What is NGS?
Next-Generation Sequencing is a terminology used to describe modern sequencing technology. This type of technology allows RNA and DNA to be sequenced much more quickly and much more cheaply than previous DNA sequencing methods, such as the Sanger sequence technology. Thanks to this, the research in molecular biology and genomics has improved greatly.
What can NGS be used for?
NGS technology has fundamentally altered the questions that doctors and researchers can ask. For example, NGS allows these professionals to:
- Quickly sequence whole genomes
- Utilize RNA sequencing to find new RNA variants.
- Quantify mRNAs or splice sites for gene expression analysis.
- Zoom in on DNA to deeply sequence target regions.
- Examine epigenetic factors like DNA protein interactions.
- Sequence cancer samples to study tumour subclones, rare variants, and more
- Study microbial diversity in the environment or humans.
The process of NGS
As we mentioned above, NGS is the sequencing of millions of DNA fragments. Described briefly, here are the steps involved in NGS:
- A DNA library is prepared from a patient’s sample. Fragmentation, amplification, and purification are used to do this.
- Individual parts of the DNA are then physically isolated. They are attached to small beads or solid surfaces.
- The sequence of every piece of the DNA is resolved simultaneously by techniques including synthesis and sequencing.
- The leftover pieces of DNA are computationally aligned against a “normal” reference genome.
- This enables the detection of any sequence alterations.
The advantages of NGS
Next-Generation Sequencing methods have several advantages. Not only do they offer high accuracy at a reduced cost, but they can also be used to detect genetic mutations of genes in patients. This means that NGS offers the promise of fundamentally altering medicine.
Another huge advantage of NGS is the amount of data it can produce. Evidence suggests that compared to capillary sequencing and other types of DNA sequencing, NGS can produce over 100 times more data.
The limitations of NGS
One of the biggest limitations is that it can be difficult for doctors and scientists to choose the most appropriate genetic test. Therefore, it is important that doctors, scientists, and researchers use a combination of different methods if they want to achieve the best and most reliable results.
The different NGS tests available
Nowadays, there is a huge range of molecular tests and NGS panels available including:
- Gene panels
- Single-gene tests
- Genome sequencing
- Exome sequencing
As there are so many different tests available, doctors and other health professionals often find it hard to select the best diagnostic method/test for their patients, particularly if they are showing signs of more than one disorder. However, it is important to note that NGS-based gene panel testing can be complemented with other ancillary methods or with array comparative genomic hybridization.
How reliable is NGS?
Next-Generation Sequencing has been proven to be exceptionally reliable. In fact, evidence suggests that mutation detection has about 95% sensitivity and 100% specificity for a range of alterations such as splicing mutations, insertions and deletions, SNPs, and gross deletions.
Evidence suggests that compared to target-based mutation analysis. proponents of NGS show high accuracy, reproducibility, precision, and robustness for clinical use.
The cost of NGS
In the past, the cost of NGS screening has been a huge deterrent. However, the price is gradually starting to decrease. Because the most important sequence variants within DNA are discovered, constant alterations are not needed. This means that NGS could save us time and money.
Evidence suggests that if we screened a population of 1,000,000 people using NGS, we would find approximately 83,421 mutation carriers.
NGS and clinical testing
Next-Generation Sequencing technology has rapidly been altered to clinical testing. Thanks to this the philosophy of clinical diagnostics is quickly changing. Over the last few years, we have seen a huge increase in the number of laboratories using NGS, leading to a better diagnosis of several inherited disorders.
NGS analyses have revolutionised the understanding of biological processes. In several clinical or basic science studies, substantive insights have been made by analyzing and comparing the DNA sequences of genes in a range of subjects. However, as most researchers will tell you, no single technique or application can tell you the whole story. Often, we need to use a range of approaches to move the research forward.
Tommy Williamson did his degree in psychology at the University of Edinburgh. He has an ongoing interest in mental health and well-being.