In search of a gene polymorphism that may contribute to the development of partial epilepsy, we focused on brain-derived neurotrophic factor (BDNF), since the functional effects of insult-induced neurotrophin changes are reported to be protection against neuronal damage and stimulation of synaptic reorganization. Two hundred nineteen patients with partial epilepsy were selected for study and 311 individuals were used as healthy controls. A single base pair (bp) polymorphism at position 240 in the non-coding region of the BDNF gene and at position 480 within the proBDNF sequence were analyzed, and the frequency of the 240T allele was found to be significantly increased in partial epilepsy patients as compared with the controls (chi(2)=8.59, P=0.0034). In contrast, no significant differences were found between the two groups in any combination of the G480A BDNF gene polymorphism. Our results suggest that the 240T allele in the BDNF gene may be a genetic marker that indicates an enhanced susceptibility to seizures, setting up a cascade leading eventually to chronic partial epilepsy in patients with such a genetic predisposition.