31 July 2008
Scientific and technical progress has led to the rapid rise in the number of genome wide association (GWA) studies and the identification of multiple gene-disease associations for common diseases. This has also resulted in the increasing commercial availability of tests to determine the presence or absence of gene variants that have shown an association with disease, although the clinical utility of many such tests is highly questionable (see previous news). Proponents of personalised genomics believe that information about genetic risk of common diseases has value as a tool for health. For example, it could potentially refine risk assessment and screening recommendations; the clinical utility of testing individuals for their genetic risk for breast cancer and its role in population screening has been discussed recently (see previous news).
However, common multi-factorial diseases such as depression, cancer and cardiovascular disease typically involve many highly complex gene-gene and gene-environment interactions, so that even when there is robust evidence to support a link between a particular genetic variant and the risk of developing a given disease, it can represent only one factor in a very complex and as yet poorly understood pathological process. There are concerns that individuals may not be able to fully understand and interpret risk information, leading to potential confusion.
In a commentary published in the August issue of Nature Genetics, McBride et al. discuss the central importance of test evaluation in the effective translation of genomic discoveries into health practices; the evaluation of genetic tests and molecular biomarkers is similarly a major work stream at the PHG Foundation. The authors call for a “targeted research programme to support translational genomics” to bridge the gap between gene disease-association research and investigations into public health and clinical utility [McBride CM et al. (2008) Nat Genet. 40(8):939-42]. Questions which need to be answered are proposed to include the best way to relay genomic risk information to patients, how advances in genome-wide sequencing methods change the nature of risk assessments, and how to educate individuals about the limitations of genetic testing. They propose a phased approach to addressing these issues due to the complexity of both the diseases and possible interventions.
The Multiplex Initiative is described as an example of a starting point for this kind of research. This aims of this project are to gain information about the reasons why individuals opt to take genetic tests and their behavioural responses to test results (see previous news). The authors note that rigorous experimentation is needed in order to provide information about whether genetic susceptibility testing should become an accepted standard of care. Other ventures such as the Corriel Personalized Medicine Collaborative are also aiming to address the clinical utility of susceptibility tests (see previous news). Data from such studies will be valuable for informing the transition from basic research to effective clinical practice, and the development of suitable guidelines and regulations on the use of genetic susceptibility tests.