PIK3CD and Dravet syndrome: In an effort to understand the molecular predictors of response to DS, we determined whether key alterations in the PI3K pathway, such as PIK3CA/PIK3R1 mutations, or PTEN alterations were associated with greater sensitivity to DS.We found that cell lines harboring oncogenic mutations in PIK3CA/PIK3R1 and PTEN alterations were significantly more sensitive than cell lines without these alterations.