Sister-chromatid exchanges are increased in epileptics, but not by sodium valproate

Sister-chromatid exchange (SCE) frequency has been studied from peripheral blood lymphocyte cultures of 21 patients with epilepsy on sodium valproate, 20 patients who had not started therapy (untreated) and 20 normal healthy controls. Treated and untreated patients with epilepsy were observed to have higher SCE frequencies (mean 9.05 and 9.82 respectively) than healthy controls (mean 4.8; P < 0.001). There was no significant difference in SCE frequency between treated and untreated patients. This suggests that the disease itself may be associated with an increased frequency of SCEs.