It may be argued that the main problem with the personal genomics industry is that its capacity for providing clinically actionable outcomes is, for the most part, anecdotal. This is not intended to be a criticism against 23andMe or any other personal genomics company, on the contrary, they have made it possible for personal genomics to become accessible to the masses.
Yet the background problem remains. We have an extremely limited knowledge of the effect that genetic variations have in our genomes, particularly those of complex traits (the majority of them) and in healthy people. The big exception, of course, is when we analyse patients born with genomic diseases. Here we have now been able to increase diagnosis for up to 40% of undiagnosed patients. Previously we were only able to confidently diagnose up to 10–15% of patients born with mental retardation, for instance.
Another promising field where genomics is having an impact is on the characterisation of tumours. Cancer, being a genetic disease, is a consequence of mutations in cells that make them proliferate out of control. Sequencing tumours can help detect the best treatment for a particular type of cancer. The sequencing of circulating tumour DNA, that is, the genetic characterisation of tumorous DNA naturally floating in blood now makes it possible for patients to have their tumour characterised without having to take a biopsia from the affected organ, which on many occasions may be stressful if not outright risky. Nevertheless, we are still in the early stages of application of sequencing for cancer treatment, as there are not enough drugs that warrant a sufficient variety of mechanisms with which to attack the many different types of cancerous cells.
So as you can see, even with the low hanging fruit (i.e., patients with genomic disorders or cancer), we have limited success in terms of tangible effects that genomics is having when applied to the clinic. For people who are healthy, the success and odds of getting clinical genetic risks correctly predicted can be even lower.
Until and unless we have a much more fine-grained detail of the molecular basis of genetic variation and its molecular consequences, we will not be in a position to be able to accomplish the long-awaited-for promise of personal genomics.
That said, genealogical services and some trait prediction algorithms are useful. Hence, what I hope is that as sequencing becomes ubiquitous and more genetic and patient data becomes available, we will be able to have a much more complete and coherent understanding of the effects of the genetic code in our health.