Human Genetics and Infection

Genetic variation in the host has a substantial influence on the course of infectious diseases caused by many microorganisms. Such interactions have been well studied in humans because the pathogens and the host genome are well characterized. In recent years, the methodology and techniques available for analyzing human genetic variation have advanced rapidly, leading to the identification of a large number of genes associated with altered susceptibility to infectious pathogens. Entire human genome sequences and millions of mapped single nucleotide polymorphisms (SNPs) provide a powerful resource for molecular analysis of differential susceptibility. Although many genes have already been associated with susceptibility to various diseases, it is likely that these represent only a small fraction of all the relevant genes. Indeed, susceptibility to most infectious diseases in humans is likely to be highly polygenic, and the identification of susceptibility and resistance genes is providing new insights into disease pathogenesis and resistance mechanisms. Conversely, it appears increasingly likely that a substantial proportion of the functional variation in the human genome has evolved to facilitate defense against infectious pathogens, leading to the observed polygenic variation in susceptibility among individuals and different human populations.