The finding in this study may be the result of several limitations. One of the main limitations of our current study was that the participants were all recruited from Jiangsu province, whereas samples obtained from the study by Sanjuán et al. (2006) were drawn from Europe, Li et al. (2013) from Shanghai, and Rao et al. (2017) from Beijing. In the study by Sanjuán et al. (2006), all individuals were Whites of Spanish descent, and the frequency of the variant allele T at rs10447760 among the controls was 0.2406, which was much higher than that of Li et al. (2013) , Rao et al. (2017), and this study (0.007, 0.006, and 0.01, respectively). Therefore, the differences in the rs10447760 polymorphism profiles suggested that the individuals from differently racial and geographic aspects might also show genetic heterogeneity of SCZ. Meanwhile, statistical results from the meta-analysis also indicated a significant heterogeneity between the studies, and different genotyping methodologies may affect the rare allele frequency, thereby causing the heterogeneity. In addition, sampling errors caused by differences in clinical diagnosis of SCZ cannot entirely be excluded.
Other limitations of our report should be considered. First, the most recent study showed that rs10447760 may be associated with clinical symptoms of SCZ (Rao et al., 2017). Because of insufficient clinical information, we could not assess the influence of these factors on the interaction between rs10447760 and SCZ. Second, our results may be influenced by the low statistical power and limited sample size because the allele T at rs10447760 is a rare variant. Third, other SNPs within the FOXP2 gene were not analyzed, and the likelihood of their modification on SCZ could not be ruled out. Fourth, the particular SNP rs10447760 is a rare variant in the study, and the P values of rare variants can be easily disturbed by a slight inaccuracy genotyping or other random factors.
The authors thank the SCZ patients and healthy participants for their cooperation in the study. This work was supported by the National Natural Science Foundation of China (81471364).
Authors’ contributions: Conceived and designed the experiments: J.Y., N.J., J.Y. Performed the experiments: J.Y., N.J., Y.L., S.Y. Analyzed the data: J.Y., N.J., C.J. F.Z. Contributed reagents/materials/analysis tools: S.Y. J.W. Wrote the paper: J.Y. N.J. J.Y. All the authors read and approved the final manuscript.
There are no conflicts of interest.
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