Factors beyond Price
However, the sequencing price freefall has stopped, or at least slowed, so that investigators have begun looking more closely at factors beyond cost; new instruments have moved in to take advantage of the needs of particular segments of the sequencing world.
For example, time to result can be critical in clinical sequencing, so taking a week just to carry out sequencing reactions and then having to analyze huge boluses of data is not an attractive option. Desktop sequencers that can turn around a sample in a day or so—but at a higher cost per Gb—have garnered a devoted following. Further advances in time-to-result and in decreasing instrument size will continue to be valued by those needing answers quickly
Indeed, the ultimate in reduced size has been actively discussed with excitement apparent for the development of portable, field-deployable instruments for sequencing samples in real-time or at remote/primitive locations.
In addition to smaller, more robust sequencing instruments, another critical need for next-gen sequencing is longer read lengths. De novo genome assemblies are still impossible with all but the smallest genomes due to repeat sequences that are longer than the read lengths. While de novo assemblies are not required in all projects, variation in copy number or genome structure can have significant impacts on data interpretation.
Multiple methods for generating real or virtual long reads have been described but none is currently available that achieves long enough reads at low enough cost to be satisfactory. Improvements in read length, either by direct sequencing or mapping very long molecules, continue to drive the development of new instruments, particularly those based on nanodetectors.
The high level of interest in the $1,000 genome and debate over the price point at which most people would want to get “their” genome sequenced obscures the fact that, in fact, no individual has a single genome that remains static over time. A low rate of mosaicism is expected across tissues in all individuals, and this variability can be very high in some cell types and will change continuously in tumors. Even more diverse and changeable is the complex set of genomes from microbes that inhabit our body surface and fluids. Thus, genomic data, though providing a solid foundation of understanding genetic effects, is only that—a foundation on which to place other genomic data.