A case of startle epilepsy associated with IL1RAPL1 gene deletion.

Startle epilepsy is a type of reflex epilepsy in which the seizures are mainly precipitated by unexpected sensory stimuli.We present an 18-month-old boy with global developmental delay and multiple episodes of loss of tone after auditory cues.The neurophysiologic study (video-electroencephalographic monitoring) revealed the epileptic nature of the stimulus-induced drop attacks, and the comparative genomic hybridization analysis revealed a microdeletion encompassing the interleukin-1 receptor accessory protein like 1 (IL1RAPL1) gene. The drop attacks were refractory to initial antiepileptic treatment, but they had a satisfactory response to a synthetic adrenocorticotropic hormone analogue.The IL1RAPL1 gene is located on Xp21.2-p21.3 and codes a synaptic adhesion protein involved in neuronal differentiation and synapse localization, stabilization, and maturation. The coexistence of startle epilepsy and IL1RAPL1 gene deletion in this child may not be coincidental and suggests a possible involvement of IL1RAPL1 in the dysregulation of excitatory synapses and the pathogenesis of startle epilepsy.