The ARX problem – how an epilepsy gene escapes exome sequencing

Silence. You might wonder why you hear very little about ARX in exome studies these days. The X-chromosomal aristaless related homeobox gene was one of the first genes for epilepsies and brain malformations to be discovered. Mutations in ARX can be identified in male patients with a variety of neurodevelopmental disorders including idiopathic West Syndrome – accordingly, it’s on the differential list for patients with Infantile Spasms without a known cause. Let me tell you about the problems that the ARX gene poses for exome sequencing. Continue reading

Three reasons why we need a new genetic literacy to understand epilepsy

ILAE Genetic Commission weekly. As you might already know, Beyond the Ion Channel has become the official blog of the Genetics Commission of the International League Against Epilepsy. Starting with this post, we would like to publish a weekly post about the issues relevant to what the ILAE-GC does. We’ll kick off this new segment by telling you about the reasons behind the Genetic Literacy Series that is currently in the works. This series of 10 papers will appear this year and next in Epilepsia. Continue reading

GABRA1 and STXBP1 as novel genes for Dravet Syndrome

Beyond SCN1A. Dravet Syndrome is a severe fever-associated epileptic encephalopathy. While the large majority of patients with Dravet Syndrome carry mutations in the SCN1A gene, the genetic basis is unknown in up to 20% of patients. Some female patients with Dravet-like epilepsies have mutations in PCDH19, but other than this, no additional major gene for typical Dravet Syndrome is known. In a recent paper in Neurology, de novo mutations in GABRA1 and STXBP1 are identified as novel causes for Dravet Syndrome. In addition, several SCN1A-negative patients were shown to have mutations in SCN1A that were initially missed. Continue reading