Hereditary Hyperekplexia in Saudi Arabia

Background Hyperekplexia is a rare disorder characterized by exaggerated startle responses to unexpected sensory stimuli, recurrent apneas, and stiffness. Only few studies have been published on this disorder in populations with high rates of consanguinity. Methods We retrospectively reviewed Saudi patients with genetically confirmed hereditary hyperekplexia using a standard questionnaire that was sent to nine major referral hospitals in Saudi Arabia. Results A total of 22 Saudi patients (11 males, 11 females) from 20 unrelated families who had hereditary hyperekplexia were included. Based on molecular studies, they were classified into different subtypes: SLC6A5 variant (12 patients, 54.5%), GLRB variant (seven patients, 31.8%), and GLRA1 variant (three patients, 13.7%). All patients were homozygous for the respective causal variant. The combined carrier frequency of hereditary hyperekplexia for the encountered founder mutations in the Saudi population is 10.9 per 10,000, which translates to a minimum disease burden of 13 patients per 1,000,000. Conclusion Our study provides comprehensive epidemiologic information, prevalence figures, and clinical characteristics of a large cohort of patients with hereditary hyperekplexia.