Studies of the association between polymorphisms of the serotonin transporter gene and fear learning have produced inconsistent results, raising questions about the strength of the relationship and the methodological conditions under which the relationship occurs. We conducted a meta-analysis of existing studies to provide an integrated statistical measure of the effect of the polymorphic region of the serotonin transporter gene (5-HTTLPR) in aversive associative learning (acquisition and extinction) in humans and rodents. The included studies were gathered through scientific database search engines. Selection criteria included experimental studies in which 5-HTTLPR and any measure of fear were considered as main variables. An effect size was calculated for each relevant experiment. 30 articles, with 33 experiments were included, 28 for acquisition, 13 for extinction. The integrated effect size (random effects model) for acquisition of fear was d = 0.33, 95 % CI [0.20, 0.50]. For extinction, the integrated effect size was d = 0.63, 95 % [CI 0.26, 1.00]. Test for publication bias was not significant neither for acquisition nor extinction. Thus, a medium but consistent effect was found between having the S allele of 5-HTTLPR and fear. The finding suggests a genetic vulnerability to anxiety in carriers of the polymorphism of the serotonin transporter that should be considered in future research.

血清素转运蛋白基因多态性与恐惧学习之间关联的研究产生了不一致的结果，对这种关系的强度和这种关系发生的方法条件提出了疑问。我们对现有研究进行了荟萃分析，以提供一个综合统计测量方法，衡量 5-羟色胺转运蛋白基因 (5-HTTLPR) 的多态性区域在人类和啮齿动物的厌恶联想学习（获得和消退）中的影响。纳入的研究是通过科学数据库搜索引擎收集的。选择标准包括实验研究，其中 5-HTTLPR 和任何恐惧测量被视为主要变量。计算每个相关实验的效果大小。30篇文章，33个实验被收录，28个用于收购，13个用于灭绝。获得恐惧的综合效应量（随机效应模型）是d  = 0.33，95% CI [0.20，0.50]。对于消光，综合效应量为d  = 0.63, 95 % [CI 0.26, 1.00]。发表偏倚测试对于获取和消退都不显着。因此，在具有 5-HTTLPR 的 S 等位基因和恐惧之间发现了中等但一致的影响。这一发现表明，在未来的研究中应该考虑血清素转运蛋白多态性携带者对焦虑的遗传易感性。