It is the small differences in the genes of each of us—our genome—that influence our individual looks, physiology, disease susceptibility, response to drugs, tastes, and innumerable other characteristics. Although we only understand a fraction of the genetic variables that define our personal traits and characteristics, interest in personal genomics is increasing and there is growing momentum for using our rapidly increasing knowledge of these individual genetic variations to personalize diagnosis and treatment in medicine.
Genotyping: Cataloging Known Gene Variations
In response to this demand, businesses have cropped up to provide personal DNA analysis. There are two ways to do this. One method is genotyping, which looks at specific locations in the DNA where particular variations are known to occur. With this approach, it is not possible to find new variations that are important, but it is possible to inventory many thousands of currently known genetic variations to identify which ones an individual has. Genotyping can be done a more easily and cheaply than DNA sequencing, the other approach to identify genetic variation.
23andMe has been offering individual genotyping for over 5 years. They were one of the first to offer this service and they are one of the most successful companies currently targeting the developing genomics market. With a recent influx of $50 million in venture capital, they appear ready to make some sort of move to expand the business.
Whole Genome DNA Sequencing
DNA sequencing, the other option for personal gene analysis, is more expensive but is getting cheaper. When the personal genomics companies started around 2007, complete sequencing of someone's DNA cost over $100K, now we are approaching a thousand bucks a genome.
Whole genome sequencing decodes all three billion A, T, C, G nucleotide bases in all of an individual’s DNA. With this information, it is possible to identify all the known significant DNA variations. In addition, with the full DNA sequence, as new ones are found, you can go back to the same data to see whether they are also present or not. The interpretation of the sequencing results will evolve with new research findings.
Personal whole genome sequencing was first offered to the general public by Knome in 2007 and cost a few hundred thousand dollars. Given the price, only a few individuals ever took advantage of this service, and more for curiosity since the information linking specific traits to DNA was even more limited than it is today—and it is still not very informative.
However, the cost of DNA sequencing has fallen precipitously since 2007. It is still relatively expensive for an individual to have their whole genome sequenced but, currently, a relatively new company, DNA DTC, offers full genome sequencing as a service directly to consumers. The price is just over $5,000.
Exome DNA Sequencing
Genes, however, only make up a few percent of genomic DNA and it is possible to ignore most of the DNA and just sequence the parts that encode genes. While some regions of DNA outside the genes may be important, in fact, most all of the genetic variations we know anything about today are in the regions that contain the genes. It is also likely that the majority of DNA variations affecting human traits will always occur in these regions since these are the active regions of our DNA. However, the situation is complicated a bit because, actually, the understanding of what a gene is has evolved, so defining these regions of DNA that contain genes is a little fuzzy.
Sequencing just part of the DNA that defines the genes, though, is a lot cheaper. This approach is called exome sequencing and still provides DNA nucleotide sequence data, but only for part of a person’s genome. So, as information evolves and new variations in certain genes are found to be important, individuals can look back at the data to see which variations they have, just like with whole genome sequencing. It is sort of a middle-ground between the fixed information genotyping can provide the all encompassing whole genome sequencing approach.
DNA DTC offers an exome sequencing service for less than $1,000, in contrast to its $5,000 whole genome sequencing service mentioned above. 23andMe also recently had a limited pilot program offering exome sequencing but have discontinued it and they have not made a decision whether to make this a permanent part of their offering.
A Growing Business Niche Based on Spit
There are a number of other companies that also offer more limited genetic analysis to anyone willing to send a bit of spit. Yes, a bit of spit. For a company to analyze your genes, you need to provide them with a sample of some part of you from which they can extract DNA. Most of the companies use spit along with maybe a scrape from the inside of the cheek (to increase the number of cells). They send a small kit to your house which contains a sealable tube and instructions about how to properly fill it with the appropriate amount of spit, then seal it, and return it. It is a very easy procedure and does not really require any professional supervision, such as might be needed for a blood sample.
Several of companies use this "spit and ship" model to provide a host of genetic tests to individuals located virtually anywhere receiving FedEx or UPS service. Many of the providers, such as, Easy-DNA and DNA Spectrum provide primarily ancestry analysis or paternity testing. However, some, like Genetic Testing Labs, Lumingenix, and deCODEme offer genotyping based on known genetic markers for diseases. However, deCODEme has recently been purchased by Amgen who appear to be shutting down this service.
The Future of Direct to Consumer Genomics Services
It remains to be seen whether other providers will enter this market that provides genomic analysis services directly to any individual, typically called the direct to consumer market. Several established companies only offer services in conjunction with health care providers. For example, Pathway Genomics, Genection, and Navigenics provide genome sequencing through healthcare providers.
FDA regulatory concerns about providing health care information directly to non-professionals may be driving the genetic analysis market away from the direct to consumer model. For example, Navigenics, mentioned above, actually started several years ago providing individual DNA analysis directly to consumers as a competitor to 23andMe, but have since changed their model.
Also, as personalized genetic data becomes more useful for healthcare and cheaper to do, it may become general practice for health providers to routinely have DNA sequencing done on patients, making it unnecessary for individuals to initiate it themselves. We're still the early days of personalized genetics and genomic medicine and it will be interesting to see how the field evolves.