Polymorphisms of the serotonin receptors genes in patients with bruxism: a systematic review

Abstract This study aimed to investigate if SNP rs6313, SNP rs2770304, SNP rs4941573, and SNP rs1923884 of the 5-HT2A receptor gene and SNP rs6295 of the 5-HT1A receptor gene are associated with bruxism etiology. Methodology This systematic review was registered in PROSPERO (CRD42018094561). A search was conducted for articles published in or before May 2021. To qualify for eligibility in this review, the studies had to be case-controls, cohort or cross-sectional. The inclusion criteria were the articles with a group of patients with bruxism and a control group in which the presence of these SNPs was evaluated. The exclusion criteria were the investigations of other polymorphisms, the studies that did not consider a control group for comparison, case reports, and reviews. The NOS and JBI were used to evaluate the methodological quality of studies. Results We conducted this study with databases, such as Web of Science, Scopus, Embase, PubMed/MEDLINE, and ProQuest. We considered four studies eligible. A total of 672 participants were included,187 with sleep bruxism, 105 with awake bruxism, 89 with sleep and awake bruxism, and 291 controls. One study found a strong association between the SNPs rs6313, rs2770304 and rs4941573 of the 5-HT2A receptor gene and sleep bruxism. In one study, we considered the C allele of the SNP rs2770304 a risk factor for sleep bruxism. We found no significant results of other SNPs in sleep bruxers compared to controls. We found no positive association concerning the SNPs and groups of awake bruxism and sleep and awake bruxism. Conclusion The different results regarding the SNPs in sleep bruxers could be explained by the genetic distinction between Chilean, Mexican, Japanese, and Polish population. More clinical trials and prospective studies must be conducted with larger sample size and in different ethnicities to confirm the results of this review.

摘要
本研究旨在探讨5-羟色胺2A受体（5-HT2A）基因的单核苷酸多态性（Single Nucleotide Polymorphism，SNP）rs6313、rs2770304、rs4941573、rs1923884，以及5-羟色胺1A受体（5-HT1A）基因的SNP rs6295是否与磨牙症的病因相关。

研究方法
本系统评价已于PROSPERO平台注册（编号CRD42018094561）。检索了2021年5月及之前发表的相关文献。本次评价纳入的研究需为病例对照研究、队列研究或横断面研究。纳入标准为：包含磨牙症患者组与对照组，且对上述SNP的携带情况进行检测的文献。排除标准包括：针对其他多态性的研究、未设置对照进行比较的研究、病例报告以及综述类文献。采用纽卡斯尔-渥太华量表（Newcastle-Ottawa Scale，NOS）与乔安娜·布里格斯研究所量表（Joanna Briggs Institute，JBI）对纳入研究的方法学质量进行评估。

结果
本研究检索了Web of Science、Scopus、Embase、PubMed/MEDLINE及ProQuest等数据库，最终纳入4项符合标准的研究。共纳入672名受试者，其中睡眠磨牙症患者187例、清醒磨牙症患者105例、同时罹患睡眠与清醒磨牙症者89例，对照组291例。1项研究显示，5-羟色胺2A受体基因的SNP rs6313、rs2770304与rs4941573与睡眠磨牙症存在显著关联；在该研究中，SNP rs2770304的C等位基因被认为是睡眠磨牙症的危险因素。与对照组相比，未发现睡眠磨牙症患者的其他SNP存在显著差异。未观察到上述SNP与清醒磨牙症组、睡眠合并清醒磨牙症组存在显著关联。

结论
睡眠磨牙症患者中SNP相关研究结果的差异，可由智利、墨西哥、日本及波兰人群的遗传异质性得到解释。未来需开展更大样本量、覆盖不同种族的临床试验与前瞻性研究，以验证本系统评价的结果。