ABSTRACT
The role of genetic factors in disease is increasingly recognized. This role ranges from causation of disease through to relatively minor alterations in susceptibility to disease and possibly, although there is not much evidence for this yet, to response to treatment. The diseases concerned range from those present at birth, to disorders manifesting themselves later in life from childhood through early to middle adulthood right through to late life conditions. This trend of identifying genetic components for an increasing number of relatively common complex disorders (e.g. multiple sclerosis, breast cancer, heart disease) is expected to continue given progressively sophisticated uses of new genetic technology. The purpose of the research that leads to the identification of genes interacting with disease is primarily to understand molecular pathogenesis in the hope that this will yield diseasemodifying treatment. However, the lag between identification of a gene and the introduction of therapies based upon that identification is measured in decades. The very first consequences of gene identification might therefore be genetic testing in all its variants and, at least until the present time, this is always accompanied by genetic counselling.
