Publications of the week: SCN8A, SYN1, ZDHHC9, and SCNM1

Power outage. This week’s publications of the week were conceptualized in complete darkness. A thunderstorm had hit the Philadelphia area on Tuesday, leading to widespread power outages in the region. I found myself in the strange position of being without power for a night, but with full strength cell phone reception and a completely charged laptop battery. Here is our post on the most relevant publications of the last few weeks, written in the calm of a dark night where the only sound around was the howling of our neighbor’s backup generator. Continue reading

The microdeletion landscape of Genetic Generalized Epilepsy

CNV. Structural genomic variations or Copy Number Variations (CNVs) significantly contribute to the genetic architecture of many neurodevelopmental disorders. However, given the enormous variation in the human genome in healthy individuals, the precise contribution of CNVs remains poorly understood. In a recent publication in PLOS Genetics, we were able to assess the microdeletion architecture in more than 1,000 patients with Genetic Generalized Epilepsy (GGE) compared to more than 5,000 controls. We found that microdeletions occur almost twice as often in GGE patients compared to controls, an analysis that revealed both known suspects and interesting candidates. Continue reading

Identifying the Doose gene – SLC6A1 mutations in Myoclonic Astatic Epilepsy

Doose Syndrome. In the early 1970s, a group of children with severe childhood epilepsies was found to have comparable clinical features that consisted of quick jerks and subsequent drop attacks amongst other types of epileptic seizures. These seizures, myoclonic-astatic or myoclonic-atonic seizures, eventually became the defining feature of an epilepsy syndrome referred to as Myoclonic Astatic Epilepsy or Doose Syndrome. In the recent issue of the American Journal of Human Genetics, we report on the first true gene for Doose Syndrome. Here is the story of SLC6A1 (GAT-1). Continue reading

Epi25 – breaking the genetic sound barrier

25,000 genomes. The epilepsy community is currently preparing for the largest sequencing project in the epilepsies so far, responding to a call by the National Human Genome Research Institute (NHGRI). If funded, the Epi25 project will allow us to begin sequencing 25,000 individuals with epilepsy, helping us to achieve the next, necessary level for gene discovery in human epilepsies. Here are some of the reasons why we need Epi25 and why you should be part of it. Continue reading

Publications of the week – Dravet Syndrome, TBC1D24, and CSTB

Issue 6/2015. Publications from the most recent issue of Epilepsia are very prominent in this week’s selection of publications. We discuss the frequency of Dravet Syndrome, a novel family with a TBC1D24 mutation, and the role of Cystatin B (CSTB) in Juvenile Myoclonic Epilepsy. Continue reading

Flickering lights, endophenotypes, and EEG genetics – CHD2 in photosensitivity

Heritable. Many epilepsy syndromes have signature EEG traits, and these traits are thought to have a strong genetic component. The endophenotype concept suggests that using these epilepsy-related traits in genetic studies will facilitate gene discovery, a concept that has failed us so far in epilepsy research, unfortunately. Now, in a recent publication in Brain, we were able to demonstrate that variants in CHD2 predispose to photosensitivity, an abnormal cortical response to flickering light. Finally, after several decades of persisting difficulties, there is some progress in the field of EEG genetics. Continue reading

SCN8A encephalopathy – and how it differs from Dravet Syndrome

Nav1.6. For some reason, SCN8A always met some resistance. In contrast to other epilepsy genes, it took a while for the community to embrace this gene as a genuine cause of epileptic encephalopathies. A recent publication in Neurology now investigates the phenotypic spectrum of SCN8A encephalopathy – and points out important features that distinguish this condition from Dravet Syndrome. Continue reading

AP4S1 in fever-associated epilepsies and spastic paraplegia

Peds vs. adult. Sometimes it makes a fundamental difference in diagnosis whether a patient is seen in a pediatric setting or by an adult specialist later in life. Here is the most recent example from our consortium, which was just published in Human Molecular Genetics: what initially looked like recessive inheritance with intellectual disability and a peculiar fever-associated epilepsy syndrome eventually turned out to be the second reported family of the novel spastic paraplegia gene AP4S1. This raises the question of how much we are missing if we are looking at the wrong point in time. Let’s have a look at how genetics can help us see an overlap of diseases where we usually don’t have a chance to. Continue reading

Beyond recessive – KCNC1 mutations in progressive myoclonus epilepsy

PME. The progressive myoclonus epilepsies (PME) are a particular subtype of seizure disorders characterized by progressive myoclonus, generalized seizures and cognitive deterioration. Known causes of PME include recessive mutations in several well-known genes, but the genetic cause is unknown in a significant proportion of patients. Now, in a recent paper in Nature Genetics, de novo mutations in KCNC1 are identified as a novel cause of progressive myoclonus epilepsies. In addition to elucidating the genetic basis in a significant subset of patients with PME, the authors demonstrate that de novo mutations play an important role in a group of diseases usually thought to be recessive. Continue reading