Dating the origin of the ccr5 delta32 Sexchat hk
Here, we investigate which disease is most likely to have generated the high frequency of We previously showed that age structuring of a host population can affect the selection of a resistance allele when the corresponding disease is responsible for significant mortality, particularly if disease virulence depends on host age and even more so if disease dynamics are episodic (31).
Thus, here we use a population genetic framework that takes into account the temporal pattern and age-specific nature of different diseases.
We divided the population into 55 age classes, each of 1 year. The systems of deterministic equations below were initiated at the stable age distribution determined by these parameters.
Stochastic effects can be ignored in a population as large as the human population in Europe several hundred years ago (34).
The allele is virtually absent in African, Asian, Middle Eastern, and American Indian populations, suggesting a recent origin, specifically estimated at 700 years based on coalescent theory (16).
The assertion that the high frequency of the variant in Europe arose through strong selection from bubonic plague (16) has become known as the classic example of the signature of historical selection on a clinically important locus.
Thus, the proportion of susceptible hosts within an age class , depends on the temporal pattern of disease transmission dynamics.
Consistent with disease time series data, we assumed that smallpox mortality peaked every 5 years, although disease mortality between these peaks was still 25% of that during the peak years (25, 28).
By comparison, smallpox was transmitted directly between humans, resulting in more continuous transmission.
deletion allele together indicate that it has been intensely selected in Europe.