As the era of gene-based medicine comes increasingly closer, current scientific research is focused on identifying genes linked with disease. A complete DNA sequence harbours many variations and differences, ranging from small changes in a single letter of code, to variations in the number of copies of a gene. These variations are the focus of extensive investigation, as researchers try to link each variation with the risk of developing certain diseases, disease prognosis, and even a prediction of patients’ responses to medications.
However, when it comes to genome sequencing, there are two limiting factors in implementing scientific findings from the bench to the clinic: the cost, and the time involved.
In response to these limitations, a research group at Imperial College London has ambitiously sought to tackle the obstacles in genomic research by patenting a technology that they propose can sequence an individual’s genome within minutes. What’s more, while current commercial sequencing costs at least a couple of thousand dollars, these researchers propose that their technology will cost a fraction of that.
“It should be significantly faster and more reliable, and would be easy to scale up to create a device with the capacity to read up to 10 million bases per second, versus the typical 10 bases per second you get with the present day single molecule real-time techniques,” stated Dr Joshua Edel, lead researcher in the study, in a press release,
In their study, published this month in the journal Nano Letters, the researchers describe this new method of chemical sequencing. They demonstrate that DNA strands can be rapidly propelled through a 50-nanometre pore, or nanopore, using an electrical charge in a silicon chip base. A tunnelling electrode junction recognizes the coding sequence as the strand comes out from the opposite face of the chip. A computer algorithm is then used to interpret the signal and construct the genome sequence.
Dr Christian Marshall, interim facility manager of The Centre for Applied Genomics’ DNA Sequencing Facility at the Hospital for Sick Children in Toronto, states that the technology appears promising. “I think the technology is really interesting, and represents an important, however minute, step towards the ultimate goal of sequencing a single DNA molecule.”
Marshall also outlines the present limitations. “Obviously there is a long way to go and many details that have to be worked out [such as computing power] in order for the technology to be feasible.”
In the next ten years, the researchers anticipate that their technology will eventually be applied to create tools yielding complete genome sequences in a single lab procedure.
“The next step,” says Dr Tim Albrecht, an author of the study, “will be to differentiate between different DNA samples and, ultimately, between individual bases within the DNA strand. […] I think we know the way forward, but it is a challenging project and we have to make many more incremental steps before our vision can be realized.”
According to Marshall, “The timeline of ten years does seem reasonable for commercial implementation, and it will be interesting to see if the technology comes to fruition and is viable in this timeframe.”
If this technology eventually makes it into the clinic, the implications for healthcare will be enormous. With rapid genome sequencing, DNA from any patient can be obtained, and a picture of their unique susceptibility to diseases can be painted, opening the door for personalized medicine.
While it’s unlikely that this technology will be readily available to patients themselves, it will be at the disposal of healthcare providers, and may be a potential tool to further guide clinical decision-making. Clinicians would be equipped to see, at the molecular level, factors contributing to a patient’s disease, and could look to current research in appropriate management.
With DNA information available for individual patients, two patients with the “same” disease may not be treated with an identical therapeutic strategy. That’s not to say that genetic information alone plays a role in elucidating disease and patient characteristics. Rather, this knowledge can be combined with current clinical and laboratory tests to provide a more robust strategy for managing disease.
If this technology proves successful, its applications span far beyond DNA sequencing. Sequence information from viral and bacterial DNA can play a role in diagnosing infectious diseases, which would bypass the culturing process currently in place. In addition, other nucleic acids such as microRNAs may be predictive of disease outcomes, and can also be sequenced through this technology.
The extent to which this technology can improve patient care is also dependent on federal and provincial healthcare models. Will the government fund or subsidize such tests? Will there be immediate barriers to implementation? In any case, the utility of such a technology cannot be ignored.
As Marshall puts it, “Beyond the low cost and speed, sequencing single molecules would help us understand somatic genomic changes and have a huge impact on personalized genomic medicine.”
