The original method of genomic sequencing took over a decade to complete. Now, next-generation sequencing can complete an entire human genome in a day. This has increased anticipation for applications of next-generation sequencing in medicine.
What Is Next-Generation Sequencing
The original method of sequencing the human genome called the Sanger sequencing technique, named after two-time Nobel laureate Frederick Sanger, produced results in a decade. Now, next-generation sequencing (NGS) can process an entire human genome in as little as a day.
How Does NGS Work
The human genome consists of two strands of DNA, twisted together in the famous “double helix” arrangement. Each strand is made up of chemicals called nucleotide bases. These bases pair with a partner along the other strand: A always pairs with T, and C always pairs with G. Each pair contains two of the four bases: adenine, thymine, guanine, and cytosine, or A, T, G, and C. Sequencing is determining the order these pairs appear along the double helix. This genetic sequence determines all the characteristics of each individual, or the “instructions” for development, that make us who we are.
Although there are various methods used to break up DNA into segments or fragments to conduct NGS sequencing, all of them perform simultaneous or parallel sequencing of those tiny pieces of DNA. Then they run an analysis against the reference database of the human genome—a public database maintained by scientists and researches that fills in any gaps in the reference sequence as new research discovers them. The genome helps medical researches determine where and in what order the genetic instructions exist to define characteristics, such as eye color, as well as abnormalities that may predict disease.
Applications in Medicine
Next-generation sequencing is just getting started in clinical application. Researchers continue to study how to “read” the human genome to identify the relationship between individual genetic codes and disease.
Current applications of next-generation sequencing in medicine include genetic counseling, which can inform prospective parents about possible future health challenges their children may face. Oncology researchers develop treatments based on genetic information from tumors. NGS can help identify previously unknown pathogens or identify the cause of unconventional disease conditions. NGS can also assist in developing treatments by identifying how these viruses and bacteria react to drugs. Sequencing helps epidemiologists track the spread of viruses by tracing transmission and identifying mutations.
Sequencing requires specialized diagnostic equipment that can direct samples into tiny channels where they can be separated for sequencing. Medical diagnostic device manufacturers work with in vitro diagnostic product development companies to design and prototype microfluidic devices that can process samples for sequencing, assisting doctors and researchers in identifying disease conditions and their causes.