As mentioned, the ratio of Mecp2 splice variants was changed at different stages of NSC differentiation. Therefore, we performed Pearson's correlation analysis between Mecp2e1/Mecp2e2 expression ratio and DNA methylation at R1, R4 and R5 (the three regions that showed significant changes) during NSC differentiation. Pearson’s correlation coefficient (r) represents the strength of correlation, with negative r indicating inverse correlation, and positive r indicating direct correlation between DNA methylation and the Mecp2e1/Mecp2e2 splice ratio. We detected a statistically significant positive correlation (r >0.9, P <0.01) between Mecp2e1/Mecp2e2 splice ratio at D2 and DNA methylation at intron 1 R4 (Additional file 3). Although it is possible that intron 1 (R4) may play a role in alternative splicing of Mecp2, further investigations are required to establish the involvement of DNA methylation in Mecp2 transcriptional splicing.
