Genetic susceptibility in infectious diseases

The outcome of infectious disease varies tremendously between individuals due to a number of factors and may therefore be viewed by the geneticist as complex traits. The identification of genes which influence disease outcome is, at present, a resource-intensive project and therefore should not be undertaken without clear evidence, preferably from twin studies, that the genetic contribution is significant. Although three principal techniques are available for the identification of disease susceptibility alleles, they are not applicable to all infectious diseases for logistical reasons. Whether a candidate polymorphic gene is identified through allele sharing studies, from interspecific crosses or taken from the currently available candidate list, the final evaluation will require carefully conducted disease association studies. As we move into the post genomic era, the identification of candidate polymorphisms and the characterization of their functional significance will rapidly increase, which will make the analysis of disease susceptibility in infectious diseases steadily more tractable.