NEXT GENERATION SEQUENCING
DNA can predict the color of your hair.
DNA can influence whether you sneeze
when you see the sun’s glare.
Through science and sharing
all of our DNA comparing.
We can learn more about ourselves
and become aware!
An interesting poem by Mason LaMarche, a founding member of the Personal Genome Learning Center at Iowa
Genome sequencing has revolutionized forensic science and with the advancements in technology and scientific methods, Next-generation sequencing (NGS) technology has emerged as an important analytical tool in the field of genomic studies where rising demands of DNA sequencing technologies adds more wings to it. According to Coherent Market Insights, Global DNA Sequencing Market is estimated to be valued at US$ 6,802.2 million in 2023 and is expected to exhibit a compound annual growth rate (CAGR) of 11.7% during the forecast period (2023-2030).
The methodologies involved have seen numerous breakthroughs and twists since the development of Sanger Sequencing in 1977, as a result of the researchers’ continual updating of the DNA library.
Talking about Sanger sequencing which was developed by Frederick Sanger in 1977, allowed scientists to determine the sequence of DNA by incorporating chain-terminating nucleotides labelled with fluorescent markers.
In the 1990s, capillary electrophoresis replaced the original gel-based Sanger sequencing, improving the speed and efficiency of DNA sequencing.
HISTORY AND EVOLUTION OF NGS:
Considering the significance of genetic data in Forensic Science, NGS has setup its relevance due to its high-throughput capacity and low cost. Next-generation sequencing (NGS) is a type of DNA sequencing technology that is based on parallel sequencing of multiple small fragments of DNA to determine sequence. This approach not only increases the speed but also reduces the cost.
454 sequencing, developed by 454 Life Sciences (later acquired by Roche), was one of the earliest NGS technologies. It used pyrosequencing to determine DNA sequences and played a pivotal role in the early NGS revolution.
Illumina, formerly Solexa, in 2006, introduced the first massively parallel sequencing platform which revolutionized the field by allowing the simultaneous sequencing of millions of DNA fragments.
Later in 2007, Applied Biosystems (later Life Technologies, then Thermo Fisher) developed SOLiD (Sequencing by Oligonucleotide Ligation and Detection) sequencing using a unique ligation-based approach.
Pacific Biosciences (PacBio) in 2010 developed single-molecule real-time (SMRT) sequencing, which observes DNA synthesis in real time by monitoring the incorporation of fluorescently labelled nucleotides.
In 2014, Oxford Nanopore Technologies introduced nanopore sequencing, a unique method that passes DNA strands through nanopores and detects changes in ionic current as nucleotides pass through the pore.
Latest NGS involves two technologies-
Second-generation sequencing technology which is based on loop array sequencing the purpose of which is to analyse a large number of samples simultaneously.
Third-generation sequencing technology which can determine the base composition of single DNA molecules.
Peter de Knijff, an innovator in forensic genomics, was among the first to recognize the possibilities for Next Generation Sequencing (NGS) in forensic applications.
Alexis Garloff, a researcher assistant from Towson University talks about life changing applications of NGS in aiding Criminal Justice System. She reveals that NGS can be used on historic human remains to aid in facial reconstructions, differentiate twins in circumstances where one twin has been suspected of a crime, or help solve cold cases by providing new leads for decade old cases. Being more sensitive and a discriminatory technique that does not require a large sample size; NGS allows a much higher chance of getting a profile from the perpetrator to enter into the Combined DNA Index System (CODIS).
FORENSIC APPLICATION OF NGS:
The application of DNA technologies in forensic investigations has rendered DNA analysis an important tool in forensic science. Since Forensic Science is the application of principles, techniques and methods of natural sciences to assist in Criminal Justice System, it becomes extremely important to devise a technique which is both accurate and efficient. Compared to other fields of natural sciences, forensic DNA analysis faces three major challenges which are as follows:
template of low copy number
highly-degraded and contaminated samples
the need for high accuracy and reproducibility considering both time and cost.
Following are some remarkable contributions of NGS technology in the field of forensic science:
Forensic Pathogen Detection: NGS can be applied in forensic microbiology to detect and identify pathogens, such as bacteria and viruses, in crime scene samples. This is useful for investigating cases involving bioterrorism or biosecurity threats. Using NGS, the entire bacterial genome’s DNA sequence may be found in a single sequence run. This information can be used to type, identify virulence and resistance, and conduct epidemic investigations.
Trace Evidence Analysis: Any kind of evidence that exists in particles small enough to be moved or switched between two surfaces covertly is commonly referred to as “trace evidence”. NGS can be used to analyze trace evidence, such as soil, pollen, and plant material, to establish links between a suspect and a crime scene.
Identification of Human Remains: A mass disaster is characterized by a situation where there is a critical mass of casualties relative to the available resources, both human and material, at the scene of an occurrence that is typically sudden and unanticipated. NGS can be employed in the identification of human remains in disaster victim identification (DVI) scenarios, where traditional methods may be insufficient. It can help match DNA from unidentified remains to reference samples from missing persons.
Mixture Deconvolution: In case of several culprits as seen in Gang rape, mixing of various biological materials such as blood, semen, saliva, vaginal discharge has been observed. NGS enables the analysis of complex DNA mixtures, where the DNA of multiple individuals is present in a sample. Advanced software and algorithms can help separate and identify individual contributors in mixed DNA samples.
FUTURE PROSPECTS:
Next-Generation Sequencing’s (NGS) future prospects are exceptionally promising. As technology develops and our knowledge of genomics expands, NGS is anticipated to be crucial in many different domains.
Efforts to reduce the cost of sequencing and streamline workflows will make NGS even more widely accessible and applicable across various fields.
NGS generates vast amounts of data, and the development of artificial intelligence and advanced data analysis tools in bioinformatics will be crucial to extract meaningful insights from these datasets.
CONCLUSION:
The sensitivity, specificity, and information content of DNA analysis in forensic science have all significantly increased because to NGS. It might offer insightful information and supporting documentation for cold cases, criminal investigations, and efforts to identify victims of disasters. Furthermore, if NGS technologies develop further, forensic applications should grow even more, providing investigators with new resources.
Author:
Divya Rani
