Objective: To evaluate whether genetic factors contribute to weight gain associated with valproate (VPA) therapy.
Research methods and procedures: We retrospectively and prospectively evaluated five pairs of monozygotic twins concordant for epilepsy and treated with VPA regarding weight course.
Results: In all twin pairs, both twins showed similar weight courses under therapy with VPA.
Discussion: These results suggest that genetic factors may have an influence on the weight change induced by VPA. Further studies are necessary to obtain heritability estimates regarding this effect of VPA therapy and to identify the relevant genes.