Genetic testing improves care for infantile-onset epilepsy: the story of SCN1A
Article first published online: 27 NOV 2012
© The Author. Developmental Medicine & Child Neurology © 2012 Mac Keith Press
Developmental Medicine & Child Neurology
Volume 55, Issue 2, pages 102–103, February 2013
How to Cite
BERG, A. T. (2013), Genetic testing improves care for infantile-onset epilepsy: the story of SCN1A. Developmental Medicine & Child Neurology, 55: 102–103. doi: 10.1111/dmcn.12037
- Issue published online: 16 JAN 2013
- Article first published online: 27 NOV 2012
Genetic testing is rapidly becoming a diagnostic modality that is more quickly and cheaply available than ever before. But just because it can be used, should it be? And how should it be used? Which patients would benefit and when? Will it make a difference to patient care and to patients’ and families’ lives?1 These are all fair questions. Healthcare utilization is a financial and, increasingly, a societal concern, yet decisions cannot be made simply based on the cost of a procedure or test, or whether it identifies a gene. Decisions must also reflect the value that such tests deliver to the patient and family, as well as their utility for informing treatment and management.2 Brunklaus et al.3 address these concerns as they relate to SCN1A testing in children with certain types of infantile-onset epilepsy. They examined the impact, as reported by the parent and physician, of a positive SCN1A test in patients with infantile epilepsy, 87% of whom were diagnosed with Dravet syndrome.
Their survey assessed the impact of the diagnosis on treatment and further diagnostic evaluations, treatment decisions, seizure control, development, and access to special services. The results speak volumes. Across all areas and for parents and physicians separately, the reported impact on all of these outcomes was substantial. Perhaps most impressive and important for anyone caring for infants with epilepsy, the impact on treatment decisions (55% changed medications) and the resulting improvements in seizure control and development (69% and 34% improved respectively) was substantial from the parents’ perspective. When SCN1A testing was done soon after the onset of epilepsy (<2y) therefore providing an early correct diagnosis, these figures were even more impressive (75%, 96%, and 79% respectively). From the physicians’ perspective, finding an SCN1A mutation allowed them to avoid further diagnostic investigations in 67% and in 99% the results were in one or more ways helpful in managing the patient.
The setting in which Brunklaus et al. performed this research is important. Most of the patients targeted for this study had Dravet syndrome and the diagnosis was likely to be suspected before the test was ordered. Dravet syndrome is a severe form of infantile-onset epilepsy. Multiple bouts of status epilepticus are common. Seizures are refractory to treatment although some medications are relatively effective in bringing seizure counts down while others exacerbate seizure occurrence. Moderate to severe intellectual disability is the typical long-term outlook. Increasing evidence suggests that uncontrolled seizures in the very young brain actually contribute to the degree of disability and that early effective intervention may actually help rescue development.4 Thus, in this particular scenario, finding an SCN1A mutation, especially early, could result in improved treatment selection leading to better seizure control and ultimately an amelioration of the typically devastating long-term developmental course of this disorder.
Negative SCN1A findings may not, in and of themselves, have great beneficial impact. Dravet syndrome, however, is only one of many genetic encephalopathic conditions that arise in the first few years of life, and which are associated with refractory seizures and lifelong disability. Increasingly, specific treatments are being found for these individual conditions which, as in the case of Dravet syndrome, may potentially improve seizure control and developmental outcome. Large-scale screening for multiple genes is becoming more and more possible. One group recently reported on a next generation sequencing panel that tests 265 genes.5 There are difficulties, no doubt, with all the information being collected when we don’t exactly know what some of it means; we are still evolving in our use of these new technologies. The research by Brunklaus et al. is an example of precisely the type of information that will help inform us about the true value of genetic testing and guide us in its use.
- 3The clinical utility of an SCN1A genetic diagnosis in infantile-onset epilepsy. Dev Med Child Neurol. DOI: 10.1111/dmcn.12030 [Epub ahead of print]., , , et al.