Brain-derived neurotrophic factor Val66met polymorphism and plasma levels in road traffic accident survivors

Background: Alterations in brain-derived neurotrophic factor (BDNF) expression and release may play a role in the pathogenesis of post-traumatic stress disorder (PTSD). Design: This study evaluated road traffic accident (RTA) survivors to determine whether PTSD and trauma-related factors were associated with plasma BDNF levels and BDNF Val66Met carrier status following RTA exposure. Methods: One hundred and twenty-three RTA survivors (mean age 33.2 years, SD?=?10.6 years; 56.9% male) were assessed 10 (SD?=?4.9) days after RTA exposure. Acute stress disorder (ASD), as assessed with the Acute Stress Disorder Scale, was present in 50 (42.0%) of the participants. Plasma BDNF levels were measured with enzyme-linked immunosorbent assay and BDNF Val66Met genotyping was performed. PTSD, as assessed with the Clinician-Administered PTSD Scale, was present in 10 (10.8%) participants at 6 months follow-up. Results: Neither BDNF Val66Met genotype nor plasma BDNF was significantly associated with the presence or severity of ASD or PTSD. Plasma BDNF levels were, however, significantly correlated with the lifetime number of trauma exposures. Conclusions: In RTA survivors, plasma BDNF levels increased with increasing number of prior trauma exposures. Plasma BDNF may, therefore, be a marker of trauma load.     

Association between MTHFR C677T polymorphism and depression: a meta-analysis in the Chinese population

Depression is a worldwide public health issue, and its prevalence increases each year. Although a number of studies have been conducted on the association between MTHFR C677T polymorphism and depression in China, this association remains elusive and controversial. To clarify the impact of MTHFR C677T polymorphism on the risk of depression, a meta-analysis was performed in the Chinese population. Relevant studies were identified using PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure and Chinese Biology Medicine through May 5, 2015. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the associations. A total of 13 case–control studies including 1895 patients and 1913 controls were involved in this meta-analysis. Overall, T variant of MTHFR C677T gene polymorphism was significantly associated with an increased risk of depression in the Chinese population (T vs. C: OR = 1.52, 95% CI = 1.24–1.85; TT + CT vs. CC: OR = 1.64, 95% CI = 1.16–2.30; TT vs. CC: OR = 2.19, 95% CI = 1.49–3.24; TT vs. CC + CT: OR = 1.80, 95% CI = 1.31–2.46). In subgroup analyses stratified by geographic area and source of controls, the significant results were found in population-based studies, in hospital-based studies, in North and South China. The risk conferred by MTHFR C677T polymorphism is higher in North China than in South China. In conclusion, this meta-analysis suggests that MTHFR C677T polymorphism is associated with depression in the Chinese population, but these associations vary in different geographic locations.     

MTHFR and ACE gene polymorphisms and risk of vascular and degenerative dementias in the elderly

Focal lacunar infarctions due to cerebral small vessel atherosclerosis or single/multiple large cortical infarcts lead to vascular dementia, and different genes and environmental factors have been implicated in causation or aggravation of the disease. Previous reports suggest that some of the risk factors may be common to both vascular as well as degenerative dementia. Among genetic factors, role of angiotensin converting enzyme (ACE) and methylene-tetrahydrofolate reductase (MTHFR) genes as putative risk factors has been examined but the outcome of these studies remain inconclusive. Present study attempted to see the importance of ACE alu insertion/deletion and MTHFR C677T polymorphisms as genetic predisposers to dementia. The study comprised of 80 vascular dementia patients, 90 degenerative dementia patients and 170 age matched controls. All were genotyped for ACE, MTHFR and APOE polymorphisms using PCR-RFLP method. Frequency of ACE D allele was seemingly high in dementia cases (26.7%) when compared to controls (11.2%). However, after adjusting for age and APOE E4^*, none of the ACE alleles showed good correlation. MTHFR genotypes or alleles also did not show any correlation. Our study suggests no true correlation of ACE or MTHR genes with dementia in elderly.     

解偶联蛋白2基因启动子-866G／A多态性与2型糖尿病的相关性研究

研究解偶联蛋白-2基因启动子常见-866G／A基因多态性（UCP2—866G／A）与2型糖尿病发病相关性。用多聚酶链反应-限制内切酶长度多态性技术检测了76例非糖尿病对照（NDM）和115例糖尿病患者（DM）的UCP2—866G／A基因型分布,并分析各基因型与胰岛功能、代谢参数的差异性。结果DM的AA基因型分布显著高于NDM（32．2％vs15．8％,χ^2=6．526,P〈0．038）。在NDM组GG型携带者空腹C肽（FCP）水平高于AA和GG组（两两比较分别为t=2．99,P=0．005和t=2．229,P=0．03）;在DM各基因型之间FCP和餐后2小时C肽（2hCP）情况与NDM对照相似,各基因型混和餐刺激后2hCP差异更加明显。结论为UCP2—866G／A基因多态性与大连地区2型糖尿病发病相关,该基因多态性主要影响胰岛β细胞分泌功能。     

TPH2基因rs4570625多态性和母亲权威教养对创造力的交互作用

采用基因分型技术、自我报告及表现性评价对409名健康的中国汉族大学生的基因型、母亲教养方式、一般智力和创造力进行测量,综合运用分层回归分析和显著性区域分析（Regions of Significance, RoS）方法探讨了TPH2基因rs4570625多态性与母亲权威教养对创造力的交互作用及其交互作用模式。结果发现：（1）在创造力的流畅性和独创性维度上,rs4570625多态性和母亲权威存在显著的交互作用。（2）RoS分析结果均支持差别易感模型,T等位基因是母亲权威的“可塑性”基因。这些发现将有助于从遗传和环境相互作用的角度解释个体创造力差异的起源。     

COMT基因Val158Met多态性与同伴关系对青少年抑郁的影响

以1048名汉族青少年为被试,采用问卷法和基因分型技术,综合运用传统回归分析和新兴的再参数化回归分析,考察COMT基因Val158Met多态性与同伴关系对青少年抑郁的交互作用模式及其性别差异。结果发现,COMT基因与同伴接纳和同伴拒绝交互预测青少年抑郁,具体表现为,在低同伴接纳或高同伴拒绝环境中,携带ValVal基因型的青少年抑郁水平高于Met等位基因携带者;在高同伴接纳或低同伴拒绝环境中,携带ValVal基因型的青少年抑郁水平低于Met等位基因携带者。此外,COMT基因与同伴接纳和同伴拒绝的交互作用与男生抑郁的关联更加密切。结果显示,COMT基因与同伴关系的交互效应为不同易感性模型提供了证据,而且该基因×环境交互效应存在性别差异。     

COMT基因多态性与攻击行为的关系

攻击行为的发生具有重要的遗传学基础。近年来, 随着分子遗传学的发展, 对攻击行为发生机制的研究已经深入到分子水平, COMT基因成为攻击行为遗传学研究的候选基因之一, 然而以人类为被试的研究结论尚存在分歧, 甚至相互矛盾。通过回顾、梳理既有关于COMT基因多态性与个体攻击行为关系的研究, 剖析了研究结论尚存在分歧和矛盾的原因, 并在此基础上从SNP标记、被试群体、研究设计、神经生物机制等几个方面展望了未来研究的方向。     

The Influence of the BDNF Val66Met Polymorphism on Mechanisms of Semantic Priming: Analyses with Drift-Diffusion Models of Masked and Unmasked Priming

Automatic and strategic processes in semantic priming can be investigated with masked and unmasked priming tasks. Unmasked priming is thought to enable strategic processes due to the conscious processing of primes, while masked priming exclusively depends on automatic processes due to the invisibility of the prime. Besides task properties, interindividual differences may alter priming effects. In a recent study, masked and unmasked priming based on mean response time (RT) and error rate (ER) differed as a function of the BDNF Val66Met polymorphism (Sanwald et al., 2020). The BDNF Val66Met polymorphism is related to the integrity of several cognitive executive functions and might thus influence the magnitude of priming. In the present study, we reanalyzed this data with drift-diffusion models. Drift-diffusion models conjointly analyze single trial RT and ER data and serve as a framework to elucidate cognitive processes underlying priming. Masked and unmasked priming effects were observed for the drift rates ν, presumably reflecting semantic preactivation. Priming effects on nondecision time t0 were especially pronounced in unmasked priming, suggesting additional conscious processes to be involved in the t0 modulation. Priming effects on the decision thresholds a may reflect a speed-accuracy tradeoff. Considering the BDNF Val66Met polymorphism, we found lowered drift rates and decision thresholds for Met allele carriers, possibly reflecting a superficial processing style in Met allele carriers. The present study shows that differences in cognitive tasks between genetic groups can be elucidated using drift-diffusion modeling.     

Association of Catechol-O-Methyltransferase Polymorphism (Val108/158Met) With Parkinson's Disease: A Meta-Analysis

Parkinson's disease (PD) is a common neurodegenerative disease, the risk factors of which are gaining more attentions. Among all these risk factors, catechol-o-methyltransferase (COMT) has been widely studied, and believed to be associated with PD. However, the relationship between COMT polymorphism and PD has not been confirmed hitherto. Therefore, a meta-analysis was performed to evaluate the effect of COMT polymorphism on PD patients. A total of 24 study subjects comprising 3,807 patients with PD and 3,942 unrelated healthy controls were recruited in this meta-analysis. Heterogeneity testing and sensitivity analysis were conducted with Review Manager 5.0 software (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark) and Stata software (StataCorp, College Station, TX), together with publication bias by funnel plot method and modified Egger's linear regression test. No evidences of publication bias and heterogeneity were detected. In the 24 studies, the estimated odds ratios (OR) in PD patients are 0.98 for the Met allele (95% confidence interval [0.92, 1.05]) under a fixed-effects model. The authors also conducted a stratified analysis according to geographic region among Europe, Asia, and North America, the ORs for the Met allele are 0.92, 1.02, and 1.10, respectively. According to the results of the meta-analysis, a conclusion could be drawn that polymorphism of Val108/158Met are not associated with the risk of PD. However, more convincing studies are warranted to have a solid conclusion supported.     

Effects of Comt Genotype on Behavioral Symptomatology in the 22q11.2 Deletion Syndrome

The 22q11.2 Deletion Syndrome (DiGeorge/velocardiofacial syndrome) is associated with elevated rates of psychosis, and is also characterized by severe attentional difficulties and executive dysfunction. Behavioral manifestations of this syndrome could result from haploinsufficiency of the catechol-O-methyltransferase (COMT) gene, located within the 22q11 region. The goal of the present study was to examine COMT genotype in relation to behavioral symptomatology in this syndrome. Val^158/108Met was genotyped in 38 patients (16 Met/-, 22 Val/-) with confirmed 22q11.2 deletions who had received the Child Behavior Checklist (CBCL) as part of a comprehensive evaluation. Results indicated that the Val genotype was associated with significantly greater internalizing and externalizing behavioral symptomatology in children with 22q11.2 deletions. Val allele status was associated with a greater-than-four-fold increase in risk for clinically significant behavior problems in children with this syndrome. These data are consistent with previous findings of increased psychopathology associated with the Val genotype in normal individuals and suggest that a functional genetic polymorphism in the 22q11 region may influence behavior in individuals with COMT haploinsufficiency.