Predictive medicine is a controversial area. It could be psychologically and emotionally draining if you are unable to take pre-emptive action to treat an illness for which you have been found to be prone to over the course of your life. Further, an increase chance of illness is not a certainty and hence the worry might be misplaced. It is also been realized that the GWAS (Genome-wide association study) on which many of the correlations are based have uncovered only a small part of the risk, so not showing up as being in danger does not imply being risk-free. The positive side of this area is that a careful study can reveal precise nature of a set of symptoms which might affect which medicines are used to treat them. Such precisions is one of the aspects of pharmacogenomics a field that seeks to match drugs to a patient's genome. Another advantage is that genetic knowledge can sometimes predict adverse reactions to drugs that have proved safe for some people but have been found to be dangerous for others.
So far the businesses entering into this field have seen mixed results. The earliest entrants were DeCODE and 23andMe. DeCODE went through a bankruptcy restructuring earlier this year. The company charges $2000 to search a sample for 1 million SNPS (single-nucleotide polymorphisms - SNP, pronounced as 'snip' is a place where a lone genetic letter varies from person to person; some 10 million SNPS (out of a forest of 3 billion) are now known) predictive of 50 genetic traits, not all of them diseases. 23andMe, based in California, charges $499 to search more than half a million SNPS for signs of 154 traits. Navigenics, a company based in California, charges $999 and restricts its analysis to 28 health conditions and 12 drug responses that can be acted upon by you and your doctor. Knome, a Massachusetts based firm, charges $68,500 to offer a bespoke whole-genome service.
It has been noted that for this field to become attractive, either the price must come down or the value of knowing "personal genomics" must go up. Both may happen when the latest generation of DNA sequencers are more widely deployed, but at the moment the gene chips provide a SNP profile rather than a complete sequence.
Source: "It's personal." The Economist, June 19th, 2010.