BACKGROUND DNA methylation is associated with non-communicable diseases (NCDs) and related traits. Methylation data on continental African ancestries are currently scarce, even though there are known genetic and epigenetic differences between ancestral groups and a high burden of NCDs in Africans. Furthermore, the degree to which current literature can be extrapolated to the understudied African populations, who have limited resources to conduct independent large-scale analysis, is not yet known. To this end, this study examines the reproducibility of previously published epigenome-wide association studies of DNA methylation conducted in different ethinicities, on factors related to NCDs, by replicating findings in 120 South African Batswana men aged 45 to 88 years. In addition, novel associations between methylation and NCD-related factors are investigated using the Illumina EPIC BeadChip. RESULTS Up to 86% of previously identified epigenome-wide associations with NCD-related traits (alcohol consumption, smoking, body mass index, waist circumference, C-reactive protein, blood lipids and age) overlapped with those observed here and a further 13% were directionally consistent. Only 1% of the replicated associations presented with effects opposite to findings in other ancestral groups. The majority of these inconcistencies were associated with population-specific genomic variance. In addition, we identified eight new 450K array CpG associations not previously reported in other ancestries, and 11 novel EPIC CpG associations with alcohol consumption. CONCLUSIONS The successful replication of existing EWAS findings in this African population demonstrates that blood-based 450K EWAS findings from commonly investigated ancestries can largely be extrapolated to ethnicities for which epigenetic data are not yet available. Possible population-specific differences in 14% of the tested associations do, however, motivate the need to include a diversity of ethnic groups in future epigenetic research. The novel associations found with the enhanced coverage of the Illumina EPIC array support its usefulness to expand epigenetic literature.

中文翻译：

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复制和扩展表观基因组范围的协会文献在南非黑人中。

背景技术DNA甲基化与非传染性疾病（NCD）和相关性状有关。尽管在祖先群体之间存在已知的遗传和表观遗传差异，并且非洲人的非传染性疾病负担很重，但非洲大陆祖先的甲基化数据目前很少。此外，目前尚不知道目前文献可以推广到受研究不足的非洲人口的程度，这些人口资源有限，无法进行独立的大规模分析。为此，本研究通过复制120名年龄在45至88岁的南非巴茨瓦纳男性中的研究结果，检查了先前发表的有关不同种族的，针对不同人群的DNA甲基化的表位全基因组关联研究的可重复性。此外，使用Illumina EPIC BeadChip研究了甲基化与NCD相关因子之间的新型关联。结果先前确定的与NCD相关特征（饮酒，吸烟，体重指数，腰围，C反应蛋白，血脂和年龄）相关的表观基因组范围关联中，多达86％与此处观察到的重叠，另有13％方向一致。只有1％的复制联想具有与其他祖先群体相反的效果。这些不一致之处多数与特定人群的基因组变异有关。此外，我们确定了8个新的450K阵列CpG关联，这些关联以前在其他祖先中均未报道，以及11个新的EPIC CpG关联与饮酒。结论在该非洲人群中成功复制了现有的EWAS发现，这表明来自经常调查的祖先的血型450K EWAS发现可以很大程度上推论到尚无表观遗传数据的种族。但是，在14％的受测联想中可能存在的特定人群差异确实激发了在未来的表观遗传研究中纳入不同种族群体的需求。随着Illumina EPIC阵列覆盖范围的扩大，发现了新颖的关联，这证明了其在扩展表观遗传学文献方面的有用性。但是，在14％的受测联想中可能存在的特定人群差异确实激发了在未来的表观遗传研究中纳入不同种族群体的需求。随着Illumina EPIC阵列覆盖范围的扩大，发现了新颖的关联，这证明了其在扩展表观遗传学文献方面的有用性。但是，在14％的受测联想中可能存在的特定人群差异确实激发了在未来的表观遗传研究中纳入不同种族群体的需求。随着Illumina EPIC阵列覆盖范围的扩大，发现了新颖的关联，这证明了其在扩展表观遗传学文献方面的有用性。