Polymorphisms of Nav1.6 sodium channel, Brain-derived Neurotrophic Factor, Catechol-O-methyltransferase and Guanosine Triphosphate Cyclohydrolase 1 genes in trigeminal neuralgia.

ABSTRACT

SUBJECTS: Trigeminal neuralgia is a neuropathic pain characterized by episodes of severe shock-like pain within the distribution of one or more divisions of the trigeminal nerve. Pain can be influenced by ethnicity, environment, gender, psychological traits, and genetics. Molecules Nav1.6 sodium channel, Brain-derived Neurotrophic Factor, Catechol-O-methyltransferase and Guanosine Triphosphate Cyclohydrolase 1 have been involved in mechanisms that underlie pain and neurological conditions. OBJECTIVE: The aim of this case-control study was to investigate the occurrence of genetic polymorphisms in Nav1.6 sodium channel (SCN8A/rs303810), Brain-derived Neurotrophic Factor (BDNF/rs6265/Val66Met), Catechol-O-methyltransferase (COMT/rs4680/Val158Met), and Guanosine Triphosphate Cyclohydrolase 1 (GCH1/rs8007267) genes in trigeminal neuralgia patients. METHODS: Ninety-six subjects were divided into two groups 48 with trigeminal neuralgia diagnosis and 48 controls. Pain was evaluated by visual analog scale and genomic DNA was obtained from oral swabs and analyzed by real-time polymerase chain reaction. RESULTS: No association was observed among SCN8A, BDNF, COMT or GCH1 polymorphisms and the presence of trigeminal neuralgia. Genotype distribution and allele frequencies did not correlate to pain severity. CONCLUSIONS: Although no association of evaluated polymorphisms and trigeminal neuralgia or pain was observed, our data contributes to the knowledge of genetic susceptibility to trigeminal neuralgia, which is very scarce. Further studies may focus on other polymorphisms and mutations, as well as on epigenetics and transcriptional regulation of these genes, in order to clarify or definitively exclude the role of Nav1.6, BDNF, COMT or GCH1 in trigeminal neuralgia susceptibility and pathophysiology.