Guenther et al. examined the CD4+, CD8+, and CD4+ CD25+ lymphocyte levels in patients over 15 years of age with active epilepsy, 15 of whom used VPA (12 as a monotherapy) and 21 of whom used LEV (17 as a monotherapy) in the pre-treatment period and in the third month of treatment. This evidence concerns the gene CD8A and epilepsy.