SCN2A and Dystonia: As for those patients with mutations in the same gene, dystonia was not necessarily present during the clinical evolution [25% (1 out of 4) in CDKL5; 50% (1 out of 2) in KCNQ2; 100% (1 out of 1) in SCN2A, (1 out of 1) in ARX and (2 out of 2) in STXBP1].