Endophenotypes for Alzheimer’s disease – GWAS on CSF tau levels

Beneath the surface. Endophenotypes sound great on paper. As the actual disease phenotype is difficult to classify and complicated, a biomarker is used for genetic analysis that is assumed to be closer to the genetic underpinnings of a disease than the disease itself. A recent study in Cell now investigates the hunt for risk factors for Alzheimer’s disease using a well-established endophenotype. The results demonstrate the complexity of endophenotypes and the difficulties in interpretation. Continue reading

Cold fusion – joining exome datasets to identify autism genes

Mergers and acquisitions. Invariably, genetic research in neurodevelopmental disorders is moving towards joint analyses of large datasets. While the methodology of meta-analysis is well established for genome-wide association studies, the joint analysis of exome datasets comes with many question marks. Now, a recent paper in PLOS Genetics pioneers the field of joint exome data analysis for association studies in autism. This paper highlights some unexpected facets of rare variant analysis. Continue reading

5 good reasons for neuroblogging – The EuroEPINOMICS blog celebrates its first birthday

Growing up. Exactly one year ago, we got serious about blogging and started posting regularly on the EuroEPINOMICS blog. Since then, we have published 145 posts on various topics regarding epilepsy, genes and the life of a scientist. In this post, we just wanted to give you five good reasons why we keep on neuroblogging. Continue reading

PGAP2 mutations and intellectual disability with elevated alkaline phosphatase

Red flags. Despite the availability of a large panel of metabolic and genetic tests as well as high-resolution neuroimaging, the cause of disease in the vast majority of patients remains unknown. This situation also applies for intellectual disability, where there is little to offer in terms of diagnostic procedures once patients are negative for array comparative genomic hybridization (array CGH). In clinical practice, we often hope that some minor clinical or biochemical features may lead us to the correct diagnosis, but in the majority of cases, these investigations lead nowhere. Now, in two back-to-back publications in the American Journal of Human Genetics, two papers describe PGAP2 mutations in patients with non-syndromal intellectual disability with elevated alkaline phosphatase.  Continue reading

The sequester and biomedical research – lessons for Europe

Transatlantic. The so-called sequester, automatic spending cuts across the board- have gone into effect in the US and also impact on the level of public funding for biomedical research. In a recent commentary in JAMA, Ezekiel Emmanuel comments on the decline of support for the NIH, which he believes goes far beyond the results of the spending cuts and can be traced back to four main factors. In this post, we would like to discuss to what extent his four main arguments also apply to the European scientific community. Continue reading

How a pathogenic de novo mutation in SCN1A ended up in the Exome Variant Server

The omics flood. Large amounts of sequence data are produced every day and we can use the genetic information of several thousand individuals as controls of any present-day genetic study. However, much of research on “traditional” epilepsy genes had been performed prior to the genomic era and often only included limited control cohorts. This begs the question whether a closer look at the currently available data might provide additional information. Now, a recent paper in the Journal of Neurogenetics investigates the presence of reported mutations for epilepsy in large, available datasets. And the results are surprising. Continue reading

FS and FS+ are two distinct diseases, as suggested by twins

GEFS+ reloaded. The genetics of Febrile Seizures (FS) is one big mystery. Even though large families have been reported and multiple linkage studies have been performed, no single susceptibility gene for Febrile Seizures is known. This is somehow surprising, given that FS is by far the most common epilepsy syndrome. In contrast to common FS, genetic research has been very successful in families with Genetic Epilepsy with Febrile Seizures Plus (GEFS+), where Febrile Seizures Plus (FS+) are the most striking feature in families.  Ever since the definition of the GEFS+ spectrum was established, the distinction from common FS has been a matter of debate. Now a twin study in Epilepsy Research suggests FS and FS+ might actually be two very distinct diseases with little genetic overlap. Continue reading

CNTN2 mutations and autosomal recessive cortical myoclonic tremor with epilepsy

Epilepsy & Tremor. The familial occurrence of epileptic seizures and chronic, non-progressive myoclonic tremor represents a peculiar genetic epilepsy syndrome for which the gene still remains elusive. Several families have been reported with autosomal dominant inheritance, and linkage to chromosomes 2, 5 and 8 have been reported. Now, the story regarding this familial syndrome gets even more enigmatic. In a recent paper in Brain, Stogmann and collaborators identify CNTN2 as the causative gene for a recessive form of cortical myoclonic tremor with epilepsy. Continue reading

The genetics of emergent phenotypes

This article was written Kevin Mitchell and first published on his blog “Wiring The Brain” and appears here with his consent.

Why are some brain disorders so common? Schizophrenia, autism and epilepsy each affect about 1% of the world’s population, over their lifetimes. Why are the specific phenotypes associated with those conditions so frequent? More generally, why do particular phenotypes exist at all? What constrains or determines the types of phenotypes we observe, out of all the variations we could conceive of? Why does a system like the brain fail in particular ways when the genetic program is messed with? Here, I consider how the difference between “concrete” and “emergent” properties of the brain may provide an explanation, or at least a useful conceptual framework. Continue reading

Familial Partial Epilepsy with Variable Foci and mutations in DEPDC5

A long story, a complicated phenotype. Massive parallel sequencing technologies were an innovation in neurogenetics and made the discovery of many genes underlying familial epilepsies possible. However, some epilepsy syndromes turned out to be more “stubborn” than others. Now, in a back-to-back submission in Nature Genetics, two groups report on the gene underlying Familial Partial Epilepsy with Variable Foci (FPEVF). And no, it’s not an ion channel this time. Continue reading