Association study of functional polymorphisms of dopaminergic pathway in epilepsy‐related factors of temporal lobe epilepsy in Brazilian population

Background and purpose There are few data about the role of neurotransmission modulated by dopamine in epilepsy, especially temporal lobe epilepsy (TLE). This is the first study that aimed to analyze the dopaminergic polymorphisms in an etiologically homogeneous group of patients with TLE with hippocampal sclerosis. Selected polymorphisms were: (i) the most expressed D2‐like receptors in the limbic system (DRD2/ANKK1 TAQ‐1A, D4_VNTR and D4_rs1800955); (ii) the dopamine transporter (DAT) 3′‐untranslated region and intron 8; and (iii) two degrading enzymes regulating the synaptic activity, i.e. the main metabolizer of dopamine, catechol‐O‐methyltransferase, and monoamine oxidase A. Methods We assessed 119 patients with unequivocal TLE with hippocampal sclerosis and 112 healthy volunteers. Individuals were genotyped for the polymorphisms of the gene encoding dopaminergic pathway transporter DAT haplotype, dopaminergic receptors, catechol‐O‐methyltransferase and monoamine oxidase A. We also evaluated epilepsy‐related factors (e.g. seizure frequency, age of onset, duration and status epilepticus). Results There was no difference between the groups for the studied polymorphisms. The polymorphism DRD4_VNTR was associated with family history of epilepsy (P = 0.003), DRD2_rs1800497 was related to status epilepticus (P = 0.022), and intron 8 VNTR DAT was related to higher seizure frequency (P = 0.019) and family history of epilepsy (P = 0.011). Conclusions Our findings demonstrated that polymorphisms of the dopaminergic pathway are associated with significant clinical features of this form of epilepsy, such as seizure frequency, family history of epilepsy and status epilepticus.