Clinical and genetic features in patients with reflex bathing epilepsy

Objective: To describe the clinical and genetic findings in a cohort of
subjects with bathing epilepsy, a rare form of reflex epilepsy. Methods:
We investigated by Sanger and targeted re-sequencing the SYN1 gene in 12
individuals from 10 different families presenting with seizures primarily
triggered by bathing or showering. Additional twelve subjects with
hot-water epilepsy were also screened. Results: In all families with
bathing epilepsy we identified 8 distinct pathogenic or likely pathogenic
variants and 2 variants of unknown significance in SYN1, nine of which are
novel. Conversely, none of the subjects with hot-water epilepsy displayed
SYN1 variants. In mutated subjects, seizures were typically triggered by
showering or bathing regardless of the water temperature. Additional
triggers included fingernail-clipping, hair-cutting, or watching someone
take a shower. Non-provoked seizures and a variable degree of
developmental delay were also common. Conclusion: bathing epilepsy is
genetically distinct reflex epilepsy mainly caused by SYN1 mutations.