The 1000 Genomes Project set out to provide a comprehensive description of common human genetic variation by applying whole-genome sequencing to a diverse set of individuals from multiple populations. Here we report completion of the project, having reconstructed the genomes of 2,504 individuals from 26 populations using a combination of low-coverage whole-genome sequencing, deep exome sequencing, and dense microarray genotyping. We characterized a broad spectrum of genetic variation, in total over 88 million variants (84.7 million single nucleotide polymorphisms (SNPs), 3.6 million short insertions/deletions (indels), and 60,000 structural variants), all phased onto high-quality haplotypes. This resource includes >99% of SNP variants with a frequency of >1% for a variety of ancestries. We describe the distribution of genetic variation across the global sample, and discuss the implications for common disease studies.

In humans, males have lower recombination rates than females over the majority of the genome, but the opposite is usually true near the telomeres. These broad-scale differences have been known for decades, yet little is known about differences at the fine scale. By combining data sets, we have collected recombination events from over 100,000 meioses and have constructed sex-specific genetic maps at a previously unachievable resolution. Here we show that, although a substantial fraction of the genome shows some degree of sexually dimorphic recombination, the vast majority of hotspots are shared between the sexes, with only a small number of putative sex-specific hotspots. Wavelet analysis indicates that most of the differences can be attributed to the fine scale, and that variation in rate between the sexes can mostly be explained by differences in hotspot magnitude, rather than location. Nonetheless, known recombination-associated genomic features, such as THE1B repeat elements, show systematic differences between the sexes.

Recombination plays a fundamental role in meiosis, ensuring the proper segregation of chromosomes and contributing to genetic diversity by generating novel combinations of alleles. Here, we use data derived from direct-to-consumer genetic testing to investigate patterns of recombination in over 4,200 families. Our analysis reveals a number of sex differences in the distribution of recombination. We find the fraction of male events occurring within hotspots to be 4.6% higher than for females. We confirm that the recombination rate increases with maternal age, while hotspot usage decreases, with no such effects observed in males. Finally, we show that the placement of female recombination events appears to become increasingly deregulated with maternal age, with an increasing fraction of events observed within closer proximity to each other than would be expected under simple models of crossover interference.

Purpose To identify single nucleotide polymorphisms (SNPs) associated with erectile dysfunction (ED) among African American prostate cancer patients treated with external beam radiation therapy (EBRT). Methods and Materials A cohort of African American prostate cancer patients treated with EBRT was followed for development of ED using the five-item Sexual Health Inventory for Men (SHIM) questionnaire. Final analysis included 27 cases (post-treatment SHIM score ≤ 7) and 52 controls (post-treatment SHIM score ≥ 16). A genome-wide association study was performed using ∼909,000 SNPs genotyped on Affymetrix 6.0 arrays. Results We identified SNP rs2268363, located in the follicle stimulating hormone receptor (FSHR) gene, as significantly associated with ED after correcting for multiple comparisons (unadjusted p-value = 5.46×10−8; Bonferroni p-value = 0.028). We identified four additional SNPs that tended toward significant association with unadjusted p-value < 10−06. Inference of population substructure revealed that cases had a higher proportion of African ancestry compared to controls (77% compared to 60%, p=0.005). A multivariate logistic regression model that incorporated estimated ancestry and four of the top-ranked SNPs was a more accurate classifier of ED than a model that included only clinical variables. Conclusions To the best of our knowledge, this is the first genome wide association study to identify SNPs associated with adverse effects resulting from radiotherapy. It is important to note that the SNP that proved significantly associated with ED is located within a gene whose encoded product plays a role in male gonad development and function. Another key finding of this project is that the four SNPs most strongly associated with ED were specific to people of African ancestry and would therefore not have been identified had a cohort of European ancestry been screened. This study demonstrates the feasibility of a genome-wide approach to investigate genetic predisposition to radiation injury.

FoxP3 ؉ CD4 ؉ regulatory T cells (Tregs) play a key role in the maintenance of peripheral self-tolerance, and it has been suggested that diabetes-susceptible nonobese diabetic (NOD) mice are defective in the generation and numbers of Tregs. We found thymic selection of Tregs to be under genetic control. Fetal thymic organ cultures on the NOD background required 3-to 10-fold more antigen than corresponding cultures on the B6 background for optimal induction of Tregs, but once the threshold for induction was reached the NOD background yielded close to 10-fold more Tregs. This increased selection of Tregs was also found in nontransgenic NOD mice in fetal through adult stages. This trait did not map to the MHC, idd3, or the chromosome 3 (Chr3) regions that control clonal deletion, but mainly to two regions on Chr1 and Chr11. Thus, NOD mice do not have a global defect in the generation or maintenance of Tregs; if anything, they show the opposite.genetic ͉ lineage commitment ͉ thymus