Background: Findings from previous studies linking brain-derived neurotrophic factor (BDNF) and schizophrenia are inconsistent and few studies have assessed the relationship between BDNF C270T gene polymorphisms and the clinical and cognitive symptoms of schizophrenia.
Aim: Compare the prevalence of the BDNF C270T gene polymorphisms between patients with schizophrenia and controls and, in the patients, assess the relationship of genotypes to the severity of symptoms.
Methods: BDNF C270T genotype and allele frequency were measured using Polymerase Chain Reaction methods in 224 drug-free patients with schizophrenia and 220 controls. Psychotic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS), and cognitive functioning was assessed using the Wisconsin Card Sorting Test (WCST) and the Trail Making Test (TMT). In the patient group, differences in severity of symptoms across the three genotypes (i.e., C/C, C/T, and T/T) of C270T were assessed using one-way analysis of variance.
Results: The frequency of the T allele was much higher in patients than in controls (15.6% vs. 4.3%, χ(2)=31.47, p<0.001) and the C/T genotype was more common among patients than controls (27.7% vs. 7.7%, χ(2)=34.93, p<0.001). Compared to controls, patients performed poorly on all the cognitive tests, but there were no significant differences in the cognitive measures between patients with the three different genotypes. The total PANSS score, the PANSS negative symptoms subscale score, and the PANSS general psychopathology subscale score were not significantly different between the three groups of patients. However, the PANSS positive symptoms subscale score showed a small, statistically significant elevation in the severity of positive symptoms in the C/T genotype compared to the C/C genotype.
Conclusion: We confirm previous findings about differences in the prevalence of the BDNF C270T gene polymorphisms in schizophrenia, but do not find strong evidence of a relationship between different genotypes and the severity of the clinical or cognitive symptoms of schizophrenia. Clinical and cognitive symptoms in schizophrenia fluctuate over the course of the illness and with treatment, so stable, individual-specific measures of these parameters (that is, traits) need to be identified before it will be possible to definitively assess their relationship to different genotypes.
背景: 关于脑源性神经营养因子(brain-derived neurotrophic factor, BDNF) 与精神分裂症的关系研究结果不尽一致，BDNF C270T基因多态性与精神分裂症精神病理症状和认知功能的关系研究较少。
目的: 比较精神分裂症患者与对照的BDNF C270T基因多态性，并评估精神分裂症患者的基因型与症状严重程度之间的关系。
方法: 采用聚合酶链反应技术检测224例未服药精神分裂症患者和220名正常人的BDNF C270T基因型和等位基因分布频率，采用阳性与阴性症状量表(Positive and Negative Syndrome Scale, PANSS)评定精神分裂症的精神病理症状，采用威斯康星卡片分类测验(Wisconsin Card Sorting Test, WCST)和连线测验(Trail Making Test, TMT)评定认知功能。采用单因素方差分析评估C270T三种不同基因型（C/C、C/T和T/T）患者症状严重程度的差异。
结果: 患者的T等位基因频率高于对照组(15.6% 比 4.3%, χ2=31.47, p<0.001)，C/T基因型更常见于患者组(27.7% 比7.7%, χ2=34.93, p<0.001)。与对照相比，患者组所有的认知测验表现均较差，但三种不同基因型患者的认知评定结果无统计学差异。三组患者的PANSS总分、PANSS阴性症状分和PANSS一般精神病理量表评分无统计学差异。但是，C/T基因型患者的PANSS阳性症状分略高于C/C基因型患者，差异具有统计学意义。
结论: 我们证实了既往报道中精神分裂症患者BDNF C270T基因多态性不一致的结果，但未发现不同基因型与精神分裂症的临床或认知症状严重程度相关的强有力证据。精神分裂症患者的临床和认知症状随病程和治疗而波动，因此需要确定稳定的、个体特异性（即特质性）的评定上述参数的指标，才有可能明确它们与不同基因型间的关系。