Asthma genetics and personalised medicine.

Unbiased genetic approaches, especially genome-wide association studies, have identified novel genetic targets in the pathogenesis of asthma, but so far these targets account for only a small proportion of the heritability of asthma. Recognition of the importance of disease heterogeneity, the need for improved disease phenotyping, and the fact that genes involved in the inception of asthma are likely to be different from those involved in severity widens the scope of asthma genetics. The identification of genes implicated in several causal pathways suggests that genetic scores could be used to capture the effect of genetic variations on individuals. Gene-environment interaction adds another layer of complexity, which is being successfully explored by epigenetic approaches. Pharmacogenetics is one example of how gene-environment interactions are already being taken into account in the identification of drug responders and non-responders, and patients most susceptible to adverse effects. Such applications represent one component of personalised medicine, an approach that places the individual at the centre of health care.