ABSTRACT
Over the past decade there has been dramatic progress in our understanding of the genetic basis of disease. Unsurprisingly as the majority of genes are expressed in the nervous system, neurology has seen the greatest developments. A decade ago only a handful of disease-causing nervous system genes were known. Now it would be the work of a large textbook to do justice to the developments and implications of this new knowledge. As we near the completion of the full human genome sequence the possibilities for exploiting this landmark achievement are huge. Initially the benefits are being seen in the rapidity and number of ‘simple’ Mendelian genes and mutations being found and described. As the basic structure of the genome and how it is transmitted is understood in finer detail the major impetus will be to use these technologies to find ‘susceptibility’ genes for common disorders. However, the techniques used to find such genes can also be used to find any genetic factor that has a biological effect; for example, the new field of pharmacogenomics is based on this approach. It is very likely that over the coming years we will understand much more about
variable drug response and idiosyncratic side-effects. This approach holds great promise for the future, as no longer will we as clinicians just have to use a trial and error approach to selection of the right drug but rather we will, using genetic testing, be able to select a drug that a patient is likely to respond to but also is unlikely to provoke serious side-effects. In addition to this ‘personalized medicine’ it can also be predicted that if an investigator knew beforehand something about the metabolic profile of the patients in a study, the design of drug trial could be greatly facilitated. This could lead to huge economies: decreasing the size of the treated groups; decreasing the risk of adverse reactions; and shortening the time of drug development. This, in turn, should decrease the cost of drug development.
