Dravet syndrome in Sweden: a population-based study.
To assess the prevalence and incidence of Dravet syndrome in children diagnosed in Sweden between 2007 and 2011, and to describe neurological comorbidity, disease course, phenotypes, and treatment effects.
All neuropaediatricians at university and county hospitals were asked to supply information for patients that matched the electro-clinical profile of Dravet syndrome. Genetic laboratories and referral clinicians were also contacted and requested to supply information.
The estimated incidence was one in 33 000 live births (95% CI 1:20 400-1:56 200) and prevalence on December 31, 2011 was one in 45 700 children aged less than 18 years of age (95% CI 1:33 800-1:63 400).
The median age of the 42 children (18 males, 24 females) was 7 years (range 1-17y), the median age at seizure onset was 6 months (range 0-12mo), and the median age at diagnosis was 3 years (range 1-14y).
A mutation in the SCN1A gene was found in 37 patients (88%), four were familial.
Intellectual disability was diagnosed in 28 (67%) children, and 18 out of 30 patients investigated had autism spectrum disorder.
Thirty participants had neurological deficits. Stiripentol, as an add-on medication, was used in 18 patients. Among these patients, seven were seizure free, six had >50% seizure reduction, and five <50% seizure reduction.
This is the first population-based study of Dravet syndrome in Sweden. Our data confirm international findings of incidence and highlights the severe and progressive course of this genetic epilepsy syndrome.