Highlights d We sequenced 20 Native American Y chromosomes chosen for their genetic diversity d A Beringian Standstill of <4,600 years led to both Siberian and American Y-lineages d Y-lineage split times rule out occupation of the Americas before 19,500 years ago d Present-day male population structure in South America arose before 12,000 years ago
We have investigated human male demographic history using 590 males from 51 populations in the Human Genome Diversity Project - Centre d’Étude du Polymorphisme Humain worldwide panel, typed with 37 Y-chromosomal Single Nucleotide Polymorphisms and 65 Y-chromosomal Short Tandem Repeats and analyzed with the program Bayesian Analysis of Trees With Internal Node Generation. The general patterns we observe show a gradient from the oldest population time to the most recent common ancestors (TMRCAs) and expansion times together with the largest effective population sizes in Africa, to the youngest times and smallest effective population sizes in the Americas. These parameters are significantly negatively correlated with distance from East Africa, and the patterns are consistent with most other studies of human variation and history. In contrast, growth rate showed a weaker correlation in the opposite direction. Y-lineage diversity and TMRCA also decrease with distance from East Africa, supporting a model of expansion with serial founder events starting from this source. A number of individual populations diverge from these general patterns, including previously documented examples such as recent expansions of the Yoruba in Africa, Basques in Europe, and Yakut in Northern Asia. However, some unexpected demographic histories were also found, including low growth rates in the Hazara and Kalash from Pakistan and recent expansion of the Mozabites in North Africa.
Observational studies examining the relationship between hypertension and breast cancer risk have reported conflicting findings. We conducted this systematic review and meta-analysis to summarize the evidence regarding the association between hypertension and risk of breast cancer. Eligible studies were identified through a comprehensive literature search of PubMed, EMBASE, and the Cochrane library until August 2016. We included observational studies that reported relative risks (RR) with corresponding 95% confidence intervals (CIs). Results from individual studies were pooled by using a random-effects model. 29 articles of 30 studies, with totally 11643 cases of breast cancer, were eligible for inclusion in the meta-analysis. We observed a statistically significant association between hypertension and increased breast cancer risk (RR: 1.15; 95% CI: 1.08, 1.22). In the subgroup analysis, we found a positive association between hypertension and breast cancer incidence among postmenopausal women (RR: 1.20; 95% CI: 1.09, 1.31). In contrast, hypertension was not associated with risk of breast cancer among premenopausal women (RR: 0.97; 95% CI: 0.84, 1.12) and Asian population (RR: 1.07; 95% CI: 0.94, 1.22).This meta-analysis collectively suggests a significantly association between hypertension and breast cancer risk, specifically for postmenopausal hypertensive women.
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