Toll-like receptors (TLRs) are cellular innate immune receptors that explore microbial molecules. For instance, TLR4 can sense bacterial lipopolysaccharides, inducing cytokines and antimicrobial peptides against the bacteria. Single-nucleotide polymorphisms (SNPs) in TLR4 are associated with diseases such as septic shock. Therefore, investigations of common SNPs may help explain the pathogenesis of diseases and various innate immune responses to infections. This study investigated genotypic frequencies of the two common TLR4 SNPs, Asp299Gly and Thr399Ile, in a Kurdish population using restriction length fragment polymorphisms (RFLPs). Global frequencies of both TLR4 SNPs in different populations of sub-Saharan Africa, North Africa, western Asia, Eurasia, and East Asia were also used to infer human migrations and past settlements. The RFLP data demonstrate that, in the Kurdish population, the genotypic frequencies of both SNPs are similar to Iranian or other West Asian populations, which in turn are comparable to Eurasian populations, suggesting past admixture due to migrations, population intermixing, and common ancestry. Globally, the frequencies of the homozygous wild-types of TLR4 variants are prevalent, but homozygous mutants are rare or lacking in almost all global populations. Frequencies of the heterozygotes varied among populations. For instance, in sub-Saharan Africa the frequency of the Asp299Gly SNP is higher than that of Thr399Ile, whereas in the Arabian Peninsula both SNPs are present at high frequencies. In contrast, East Asian populations lack or have very low frequencies of both TLR4 SNPs of interest. Moreover, co-segregation of the TLR4 SNPs is common in some populations, which may indicate important associations with certain diseases. Future studies are required to link the TLR4 SNPs with either resistance or susceptibility to diseases.

中文翻译：

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库尔德人群中常见 TLR4 SNP 的基因型频率：全球回顾和非洲外迁移。

Toll 样受体 (TLR) 是探索微生物分子的细胞先天免疫受体。例如，TL​​R4可以感知细菌脂多糖，诱导细胞因子和抗菌肽对抗细菌。TLR4 中的单核苷酸多态性 (SNP) 与感染性休克等疾病相关。因此，对常见 SNP 的研究可能有助于解释疾病的发病机制以及对感染的各种先天免疫反应。本研究使用限制性长度片段多态性 (RFLP) 调查了库尔德人群中两种常见 TLR4 SNP（Asp299Gly 和 Thr399Ile）的基因型频率。撒哈拉以南非洲、北非、西亚、欧亚大陆和东亚不同人群中两种 TLR4 SNP 的全球频率也被用来推断人类迁徙和过去的定居点。RFLP 数据表明，在库尔德人群中，两个 SNP 的基因型频率与伊朗或其他西亚人群相似，而这些人群又与欧亚人群相当，表明过去由于迁移、人群混合和共同血统而发生混合。在全球范围内，TLR4 变异纯合野生型的频率很普遍，但纯合突变体在全球几乎所有人群中都很罕见或缺乏。杂合子的频率因人群而异。例如，在撒哈拉以南非洲，Asp299Gly SNP 的频率高于 Thr399Ile，而在阿拉伯半岛，这两个 SNP 的出现频率都很高。相比之下，东亚人群缺乏或频率非常低的两个感兴趣的 TLR4 SNP。此外，TLR4 SNP 的共分离在某些人群中很常见，这可能表明与某些疾病存在重要关联。未来的研究需要将 TLR4 SNP 与疾病抵抗力或易感性联系起来。