Breast cancer (BC), a heterogeneous, aggressive illness with high mortality, is essentially a genomic disease. While the high-penetrance genes BRCA1 and BRCA2 play important roles in tumorigenesis, moderate- and low-penetrance genes are also involved. Single-nucleotide polymorphisms (SNPs) in microRNA (miRNA) genes have recently been identified as BC risk factors. miRNA genes are currently classified as low-penetrance. SNPs are the most common variations in the human genome. While the role of miRNA SNPs in BC susceptibility has been studied extensively, results have been inconsistent. This review analyzes the results of association studies between miRNA SNPs and BC risk from countries around the world. We conclude that: (a) By continent, the largest proportion of studies to date were conducted in Asia (65.0 %) and the smallest proportion in Africa (1.8 %); (b) Association studies have been completed for 67 different SNPs; (c) 146a, 196a2, 499, 27a, and 423 are the most-studied miRNAs; (d) The SNPs rs2910164 (miRNA-146a), rs11614913 (miRNA-196a2), rs3746444 (miRNA-499) and rs6505162 (miRNA-423) were the most widely associated with increased BC risk; (e) The majority of studies had small samples, which may affect the precision and power of the results; and (f) The effect of an SNP on BC risk depends on the ethnicity of the population. This review also discusses potential explanations for controversial findings.

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miRNA 中单核苷酸多态性与乳腺癌风险之间的关联：更新的综述

乳腺癌 (BC) 是一种具有高死亡率的异质性侵袭性疾病，本质上是一种基因组疾病。虽然高外显率基因 BRCA1 和 BRCA2 在肿瘤发生中起重要作用，但中低外显率基因也参与其中。microRNA (miRNA) 基因中的单核苷酸多态性 (SNP) 最近已被确定为 BC 风险因素。miRNA 基因目前被归类为低外显率。SNP是人类基因组中最常见的变异。虽然 miRNA SNP 在 BC 易感性中的作用已被广泛研究，但结果并不一致。本综述分析了世界各国 miRNA SNP 与 BC 风险之间的关联研究结果。我们得出的结论是：(a) 按大陆划分，迄今为止最大比例的研究是在亚洲进行的（65. 0 %）和非洲最小的比例（1.8 %）；(b) 已完成 67 个不同 SNP 的关联研究；(c) 146a、196a2、499、27a 和 423 是研究最多的 miRNA；(d) SNP rs2910164 (miRNA-146a)、rs11614913 (miRNA-196a2)、rs3746444 (miRNA-499) 和 rs6505162 (miRNA-423) 与 BC 风险增加最广泛相关；(e) 大多数研究样本量小，可能影响结果的精确度和效力；(f) SNP 对 BC 风险的影响取决于人口的种族。本综述还讨论了对有争议的发现的潜在解释。rs3746444 (miRNA-499) 和 rs6505162 (miRNA-423) 与 BC 风险增加最广泛相关；(e) 大多数研究样本量小，可能影响结果的精确度和效力；(f) SNP 对 BC 风险的影响取决于人口的种族。本综述还讨论了对有争议的发现的潜在解释。rs3746444 (miRNA-499) 和 rs6505162 (miRNA-423) 与 BC 风险增加最广泛相关；(e) 大多数研究样本量小，可能影响结果的精确度和效力；(f) SNP 对 BC 风险的影响取决于人口的种族。本综述还讨论了对有争议的发现的潜在解释。