Susceptibility. Two weeks ago, we published a post on rare variants in SCN9A as potential susceptibility genes for Dravet Syndrome with mutations in SCN1A. Ever since reading the article by Mulley and collaborators, I had tried to come up with an idea of what the genetic architecture might look like if both de novo variants and inherited variants contribute. I wanted to follow up on my earlier post with this brief back-of-the-envelope calculation. Continue reading
Category Archives: Opinion
The endozepine mystery
Compound unknown. GABA is the main inhibitory neurotransmitter in the Central Nervous System and its effect is mediated through GABA receptors. Benzodiazepines are compounds that reinforce the action of GABA in the brain, which gives them antiepileptic properties. Consequently, benzodiazepines are one of the most common groups of antiepileptic drugs used to interrupt acute epileptic seizures. Interestingly, benzodiazepines have their own binding site on the GABA receptor, suggesting that they might actually mimic the effect of another, yet unknown substance that is present in the brain. The identity of this mysterious substance, the endogenous benzodiazepine or endozepine, has been one the romantic mysteries of neuroscience. Now, a recent paper in Neuron provides strong evidence that products of the DBI gene are the long-sought endozepine. Continue reading
Three things the beach taught me about science
Endless summer. I am quoting from a representative email that I received this summer from a fellow scientist in the EuroEPINOMICS consortium: “XYZ will reply to you once he is back from his holiday – IF he comes back”. A metereological anomaly had given us one of the longest and most intense summers that I can remember. No rain for roughly four weeks, a new temperature record and a heat that was so intense that the tarmac on the highways started to melt. Accordingly, the motivation in EuroEPINOMICS land to leave the beach behind and return to the office was at an all time low. We spent our summer holiday in Marielyst, Denmark and I just wanted to share some thoughts on how the world of science looks when you’re at the beach. Yes, this post is not too serious. Continue reading
Invitation for the 2013 Young Researchers Meeting
This time, the desert. After the successful meeting for Young Researchers in Epileptology in Kiel last year, we would like to invite young and senior researchers in the field for the 2013 meeting, which will take place on December 14th, 2013 in Sde Boker, Israel. This year’s meeting is embedded in a small international meeting from Dec 12th-14th on epilepsy genetics with the primary aim of bringing together researchers from Israel and Palestine. As last year, we would like to extend the invitation for this year’s Young Researchers Meeting in Epileptology to all young scientists involved in the field. Don’t forget to bring water and sunscreen; we’re going to the Negev Desert. Continue reading
GRIN2A encephalopathy, epilepsy-aphasia and rolandic spikes
The GRIN2A triple. The idiopathic focal epilepsies are a group of childhood seizure disorders ranging from mild, self-limiting rolandic epilepsy to severe epileptic encephalopathies. The EEG feature of sharp-slow waves originating from the rolandic region is the unifying feature. As the rolandic region is part of the brain regions involved in speech production, acquired aphasia, i.e. loss of speech, can be a prominent feature in some patients. A strong genetic contribution in idiopathic focal epilepsies is assumed, but the genes involved have remained largely elusive. Now, three back-to-back publications in Nature Genetics highlight a prominent role of GRIN2A, probably the most counter-intuitive epilepsy gene ever found. Continue reading
Reinventing a consortium – the RES data sharing policy
Share or be shared. During the last two weeks, the RES consortium has approved a new data sharing policy that will allow us to work with increased transparency and accountability within our upcoming projects. This new data sharing policy is a consequent extension of the previous protocols we had in earlier consortia – with one major difference. This time, it’s in writing. While we are getting ready to tackle the large dataset on epileptic encephalopathies released by the Sanger Institute, we took a moment to talk about how things should be running.
Genetic imaging in Dravet Syndrome – variation on a theme?
Networks in the brain. While I am waiting to hear back about my ERC starting grant application on genetic imaging, I wanted to use the waiting time to introduce a small pioneer study that we performed on functional imaging in Dravet Syndrome. Dravet Syndrome, one of the most prominent genetic epileptic encephalopathies, is due to mutations in SCN1A. The EEG findings progress from an initially unremarkable EEG to frequent generalized activity. Functional MRI offers a possibility to investigate the network underlying these discharges and to pinpoint brain regions involved in generating the epileptiform activity. Given that patients have a common genetic finding, the assumption that discharges are generated by identical networks is intriguing. However, we found that things might not be as simple as that. Continue reading
Transmission of rare variants in parent-offspring trios – power or no power?
My untested assumption. Recently, I have boasted quite a bit about the power of the trio design, i.e. the inclusion of patients and parents in the analysis of rare genetic variants. Rare variants, in contrast to monogenic variants that arise de novo, are usually transmitted from unaffected parents and are the big unknown of modern day genetic studies. Much of the missing heritability may be accounted for by rare variants, but identifying these variants from genomic noise is difficult. Power calculations for association studies usually suggest that thousands, if not tens of thousands, of patients are necessary to identify these variants with sufficient statistical certainty, a sample size that the field of epilepsy research may never arrive at. So what about switching to parent-offspring trios? Would this help us? Follow me on a brief statistical journey through the land of rare variants. Continue reading
Genes, patents and the Myriad story
When genes meet the law. Last week, the Supreme Court of the United States of America (SCOTUS) ruled that genes are not patentable, a decision that will be known as the “Myriad Decision”, named after Myriad Genetics, a commercial laboratory that is the single provider for BRCA1/2 testing in breast cancer and ovarian cancer in the United States. For more than a decade, Myriad has had virtually exclusive rights to the genetic analysis of both genes, given a large number of patents surrounding BRCA1/2 analysis. Continue reading
Dealing with the genetic incidentaloma – the ACMG recommendations on incidental findings in clinical exome and genome sequencing
Clinical genome sequencing. While exome and genome sequencing is widely used as a research tool, these technologies are also routinely applied in a clinical setting. As with many other data-rich diagnostic tests in medicine, there is an ongoing question on how to deal with potentially relevant findings that turn up indicentally. Now the American College of Medical Genetics and Genomics (ACMG) has released their long-expected recommendations on data return of incidental findings in clinical exome and genome sequencing. Their recommendations provide an interesting basis for discussion on what to do with genetic findings that are found by chance. Continue reading