SCN1A and Dravet syndrome: However, based on an estimated prevalence of Dravet syndrome of 1∶20,000 to 1∶40,000,[8]–[10] a proportion of vaccination-related seizures in children with Dravet syndrome of 27%,[17] and a proportion of detectable SCN1A-mutations of 70%, [12] the expected number of SCN1A-related Dravet syndrome among children with seizures following vaccination would be between 9 and 19 in this ten-year birth cohort of 1,97 million live births.[35] This is in agreement with our results.