Background: During the past decade, the genetic causes of monogenic forms of disease have been successfully defined; this work has helped the progression of basic scientific investigation into many disorders, and has helped to characterise several molecular biological processes. An important goal of genetic research is to extend this work and define genetic risk factor loci for complex disorders. The aim is for these data not only to offer further basic understanding of the disease process, but also to provide the opportunity to obtain genetic risk assessments that could be generalised to the public.
Recent developments: The development of resources such as the Human Genome Project and the International Human Haplotype Map Project, coupled with technological advances in ultra-high-throughput genotyping, have provided the basis for genome-wide association studies (GWAS). This approach has been successful for several complex disorders in a short time. Although GWAS are still a new method, these studies have been used for a small number of neurological disorders and, despite varied results for these conditions, GWAS can usefully show the power and limitations of this approach. WHERE NEXT?: GWAS have the potential to show and emphasise common genetic variability associated with disease. However, a challenge of this approach is that large sample series and considerable resources are required. One important consideration will be the interpretation of the results of GWAS in a clinically meaningful way and to discern the implications for all therapy areas, including neurological disorders; this challenge will require specialised skills and resources from both the medical and the scientific communities.