NRGN is one of the most promising candidate genes for schizophrenia based on function and position. Therefore, this study aimed to examine the genetic association of this polymorphism with schizophrenia in the Zhuang and Han populations of south China.

A total of 282 patients (188 Han and 94 Zhuang) and 282 healthy subjects (188 Han and 94 Zhuang) were recruited. Of these, 246 schizophrenia patients underwent an assessment of psychotic symptoms using the Positive and Negative Syndrome Scale (PANSS). A TaqMan genotyping assay method was used to determine the genotypes.

We did not find a significant association of rs12807809 polymorphism with schizophrenia in the total pooled samples, or in the separate ethnic groups. However, in Han schizophrenia patients, quantitative data analyses showed that the CC genotype of the rs12807809 polymorphism was associated with PANSS aggression subscale score and activation subscale score. Furthermore, carriers of the C allele of rs12807809 polymorphism among Han schizophrenia patients had higher scores of general, activation, depression, aggression, and global symptoms than the T allele carriers.

In conclusion rs12807809 polymorphism may not contribute to the risk of schizophrenia but influence the clinical symptoms of schizophrenia in the Han population.

Schizophrenia (SZ) is a common severe psychiatric disorder and a complex polygenic inherited disease that has not yet been fully interpreted. Heredity was proven to play an important role in the development of SZ. The association between the NOTCH4 gene rs3131296 polymorphism and SZ was reported to reach significance at the genome-wide level; therefore, it is necessary to replicate this association in other different populations.

To evaluate the association of the NOTCH4 gene rs3131296 polymorphism with the risk for SZ, and to explore whether a significant association could be replicated in different ethnic groups of China, we conducted this case–control study on 282 SZ cases (188 Han and 94 Zhuang) and 282 controls (188 Han and 94 Zhuang) among the Chinese Zhuang and Han populations.

The results showed no statistically significant difference in the genotype or allele frequencies of the NOTCH4 gene variant rs3131296 between SZ patients and healthy controls in either the Zhuang or Han samples (p > 0.05). In addition, no significant difference was found in genotype or allele frequencies of the NOTCH4 gene variant rs3131296 between cases and controls in the combined samples including Zhuang and Han samples.

Our study failed to replicate the significant association between the NOTCH4 gene rs3131296 polymorphism and the risk for SZ.

Schizophrenia (SCZ) and bipolar disorder (BD) are common psychotic disorders, which show some overlaps in genetic aetiology. Researchers have conducted a number of studies to investigate the relationship between SCZ and the 1354C/T genetic polymorphism of 5-hydroxytryptamine receptor 2A (HTR2A–1354C/T), as well as the associations between BD and the HTR2A–1354C/T polymorphism. However, the results were conflicting. To provide a more robust estimate about the effects of the HTR2A–1354C/T polymorphism on the risk of these two psychotic disorders, we performed this meta-analysis.

We used the pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) to investigate the relationships between SCZ and the 1354C/T polymorphism of HTR2A, as well as the associations between BD and HTR2A–1354C/T. Publication bias was tested by Begg's test and inverted funnel plot, and heterogeneity was checked by Cochran's Q statistic and the inconsistency index (I2).

Eight studies were concerned with SCZ, analysing a cumulative total of 2953 cases and 3153 controls; six papers studied BD, using a total of 923 cases and 928 controls. There was no significant association found between HTR2A–1354C/T and SCZ in the overall population (T allele vs. C allele, OR = 1.035, 95% CI 0.912–1.175, p = 0.596) or in the subgroups Caucasian population and Asian population. Moreover, there was no significant association between the HTR2A–1354C/T polymorphism and BD in the overall population (T allele vs. C allele, OR = 1.038, 95% CI = 0.607–1.772, p = 0.892).

On the basis of these results, the HTR2A–1354C/T polymorphism is unlikely to be a risk factor for SCZ and BD.