The genetics of common diseases: the implications of population variability.

The results of recent work on the inheritance of susceptibility to malaria suggest that, over what may have been a relatively short evolutionary period, a remarkably diverse series of gene families have been modified in response to the selective drive of this infectious disease. The phenotypic consequences are not confined to the erythrocyte, they also involve the immune system, cytokines and many other systems. It seems likely that the mechanisms of genetic susceptibility to current environmental agents will reflect at least a similar degree of complexity and, if the selective pressures have been present for longer periods of our evolutionary history, may be even more diverse. These issues are discussed in the light of current efforts to identify some of the major genes involved in variation in susceptibility to the common non-infectious diseases of the developed world.