Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Dec 2019
Bottleneck and selection in the germline and maternal age influence transmission of mitochondrial DNA in human pedigrees.
Heteroplasmy-the presence of multiple mitochondrial DNA (mtDNA) haplotypes in an individual-can lead to numerous mitochondrial diseases. The presentation of such diseases depends on the frequency of the heteroplasmic variant in tissues, which, in turn, depends on the dynamics of mtDNA transmissions during germline and somatic development. Thus, understanding and predicting these dynamics between generations and within individuals is medically relevant. ⋯ We show that heteroplasmic variants at intermediate frequencies can segregate for many generations in the human population, despite the strong germline bottleneck. We show that selection acts during germline development to keep the frequency of putatively deleterious variants from rising. Our findings have important applications for clinical genetics and genetic counseling.
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Proc. Natl. Acad. Sci. U.S.A. · Dec 2019
Local demographic changes and US presidential voting, 2012 to 2016.
Immigration and demographic change have become highly salient in American politics, partly because of the 2016 campaign of Donald Trump. Previous research indicates that local influxes of immigrants or unfamiliar ethnic groups can generate threatened responses, but has either focused on nonelectoral outcomes or analyzed elections in large geographic units, such as counties. ⋯ We employ regression analyses varying model specifications and measures of demographic change. Our estimates uncover little evidence that influxes of Hispanics or noncitizen immigrants benefited Trump relative to past Republicans, instead consistently showing that such changes were associated with shifts to Trump's opponent.