男性同性恋（MSM）人群的抑郁症状患病率远高于一般人群，由抑郁症状导致的自残、自杀、物质滥用等问题严重影响该人群的身心健康，对其病因学研究具有重要意义。MSM人群抑郁症状病因学研究既往主要集中在应激、素质等社会心理行为方面，而近年研究显示，遗传因素在抑郁症状发生中具有重要作用，相关研究提示男性同性恋与抑郁症状可能存在共享的遗传机制，而5-羟色胺（5-HT)相关基因多态性是潜在的重要共享遗传机制。项目组基于前期对该人群抑郁症状患病率及其影响因素、性取向的遗传与环境因素交互作用机制研究基础上，拟采用病例对照研究设计，分别在MSM人群和男性异性恋人群中探讨应激、素质因素及5-HT相关基因多态性与抑郁症状之间的关联，构建包含5-HT相关基因多态性在内的MSM人群抑郁症状的整合素质—应激模型，分析各个因素间的调节效应和中介效应，并深入探讨MSM人群抑郁症状易感机制，为MSM人群抑郁症状干预提供依据。

Compared to the general population, men who have sex with men (MSM) suffer from more mental health problems. In the preliminary research works, our research group found that the prevalence of depressive symptoms in MSM population was much higher than in general population. However, the mechanism of high incidence of depressive symptoms in MSM has not been fully elucidated. Previous researches suggest that depressive symptoms in MSM population is associated with stress, diathesis and genetic factors. But each of these factors cannot fully explain the mechanism. There are also some previous researches suggest that shared genetic mechanisms of depressive symptoms and male sexual orientation are existing, and 5-HT related gene polymorphisms probably are the shared genetic mechanisms. In this study, we intend to use case-control study design, explore the associations among depressive symptoms, stress, diathesis and genetic factors in MSM and general population, respectively. And further compare these associations in two groups, thereby demonstrate the strength and characteristics of these associations in MSM. On this basis, using Structural equation modeling to containing the integrated diathesis-stress models of depressive symptoms in MSM. And the mediating effect and moderating effect of each factors also will be examined. In this study, the mechanisms of susceptibility of depressive symptoms in MSM will be explored comprehensively, and scientific basis for developing interventions for depressive symptoms in MSM population will be provided. This study has important public health significance.