Anti-epileptic drugs with Na+ channel blocking activity improve QTc in individuals with Rett syndrome. Anti-epileptic drugs with Na+ channel blocking activity improve QTc in individuals with Rett syndrome. (A) Individuals with RTT that have a QTc >450 ms show significant improvement on QTc status after AED therapy was initiated. (B) Treatment with AEDs decreased the QTc status of 70% of the individuals that have LQT below the 450 ms LQT threshold. (C) There was no significant effect on QTc status post AED therapy in individuals with a normal QTc <450 ms, but (D) there was an increase in QTc in 20.3% of the individuals. Prolonged QTc >450 ms with AEDs, n=10; normal QTc <450 ms with AEDs, n=54. **P=0.005 (paired Student’s t-test). José A. Herrera et al. Dis. Model. Mech. 2015;8:363-371 © 2015. Published by The Company of Biologists Ltd