Recent Explosive Human Population Growth Has Resulted in an Excess of Rare Genetic Variants
Exponential Growth Effects Humans are an extraordinarily successful species, as measured by our large population size approximately 7 billion much of which can be put down to recent explosive growth. Leveraging human genomic data, Keinan and Clark (p. 740) examined the effects of population growth on our ability to detect rare genetic variants, those hypothesized to be most likely associated with disease. It appears that rapid recent growth increases the load of rare variants and is likely to play an important role in the individual genetic burden of complex disease risk. Genetic models that incorporate recent human population growth can better identify mutations in large samples. Human populations have experienced recent explosive growth, expanding by at least three orders of magnitude over the past 400 generations. This departure from equilibrium skews patterns of genetic variation and distorts basic principles of population genetics. We characterized the empirical signatures of explosive growth on the site frequency spectrum and found that the discrepancy in rare variant abundance across demographic modeling studies is mostly due to differences in sample size. Rapid recent growth increases the load of rare variants and is likely to play a role in the individual genetic burden of complex disease risk. Hence, the extreme recent human population growth needs to be taken into consideration in studying the genetics of complex diseases and traits.
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