Predisposition to epilepsy in fragile X syndrome: does the Val66Met polymorphism in the BDNF gene play a role?

ABSTRACT

Epilepsy is detected in about 23% of patients with fragile X syndrome (FXS). Absence or reduced levels of the fragile X mental retardation protein (FMRP), a global regulator of translation in neurons and an important factor in synaptic plasticity, produce the observed epileptic patterns. The brain-derived neurotrophic factor (BDNF) gene is a specific regulator of synaptic plasticity, and disturbances in its function cause dendrite abnormalities similar to those observed in FXS. A putative reciprocal regulation of FMRP and BDNF has been hypothesized. The Val66Met polymorphism in the BDNF gene may be involved in the alteration of normal secretion of the mature peptide and may modulate the epileptic phenotype observed in some patients with FXS. We investigated the relationship of this Met66 allele to the prevalence of epilepsy in 77 patients with FXS. No association was observed between this polymorphism and epilepsy in our group of patients. Therefore, it should not be considered a biomarker for developing epilepsy in patients with FXS.