GDNF and Dravet syndrome: There was no significant difference in the GDNF levels of the patients (DS and NDS) and HC (527.32 ± 136.86 pg/ml vs. 587.03 ± 193.90 pg/ml vs. 547.49 ± 134.66 pg/ml, F = 1.992, p = 0.140) (Fig. 1b).