As a technology, however, genotype based tests have several inherent advantages over non-genetic tests. Genotype based assays are cheap, have high fidelity, and can be multiplexed, in contrast to multiple phenotypic risk factors and biomarkers, many of which require different methods for their measurement, and which are more affected by biological variability and measurement error than is genotyping. Moreover, because genotype is invariant it offers the prospect of risk assessment from much earlier in life than is possible with phenotype based tests. In the case of cardiovascular risk factors, evidence shows that greater benefits accrue from earlier intervention among people at higher risk (for example, in the form of smoking cessation or cholesterol lowering).45 46 The findings of our study should thus not lead to the premature dismissal of genotype based risk prediction as a health technology. Rather, increased efforts should be made to understand the strengths and limitations of such tests as well as their optimal place in health care, a conclusion highlighted in the recent House of Lords Science and Technology Committee’s report on genomic medicine (www.publications.parliament.uk/pa/ld200809/ldselect/ldsctech/107/107i.pdf).
