Genotype determination of epileptic patients for ABCB1-T1236C polymorphism based on digestion of a 240 bp amplified DNA fragment with HaeIII, analyzed by 2.5% agarose gel electrophoresis. Lanes 1-4 and 7, digestion resulted in two DNA fragments of 204 bp and 36 bp (CC genotype); lanes 5 and 8, digestion resulted in three DNA fragments of 240 bp, 204 bp and 36 bp (TC genotype); lane 6, fragment with no digestion site (TT genotype); M, 100 bp DNA ladder; C1 and C2 sequenced fragments with site for digestion in one or both alleles, as positive controls.