Beyond the Ion Channel – and back

Where do all the ion channels come from? I would like to start off with a brief commentary about the current state of gene discovery in human epilepsy. Some of our readers rightfully took offense to my previous statement that gene discovery in epilepsy it over – quite the contrary is true, and I apologize for any confusion that I may have caused. Gene discovery in epilepsy is one of the few areas of human genetics with an ongoing, rapid sequence of gene discovery with a tremendous translational potential. But we also need to reconsider the name of this blog – we are far from being beyond the ion channel. The ion channel concept has made a remarkable return in human epilepsy genetics. Let’s find out why. Continue reading

SETBP1, ZMYND11, and the power of joint exome and CNV analysis

Parallel worlds. There are two fields of genetics for neurodevelopmental disorders that currently produce large amounts of data – the field of copy number variation analysis and the field of exome sequencing. When assigning pathogenicity, information from both genetic technologies are rarely considered jointly. A recent study in Nature Genetics now performs a combined analysis of a large CNV and exome datasets in intellectual disability and autism. Interestingly, this method produces robust results, highlighting novel causative genes. Continue reading

Dynamin 1, the synapse, and why epilepsy gene discovery is now officially over

E2 consortium. Infantile Spasms and Lennox-Gastaut Syndrome are two epilepsy syndromes with a strong genetic component. De novo mutations play an important role in genetic epilepsies. However, given the overall mutational noise in the human genome, telling causative genes from innocent bystanders is difficult. In the largest and most comprehensive analysis so far, our E2 consortium just published a joint analysis of 356 patient-parent trios, which were analyzed by exome sequencing. In addition to implicating DNM1, GABBR2, FASN, and RYR3, this publication sends a clear message: the age of gene discovery in epilepsy is over – from now on, genes will find themselves. Let me tell you what I mean by this. Continue reading

Beneath the surface – the role of small inherited CNVs in autism

Grey zone. Structural genomic variants or copy number variations (CNV) can be reliably assessed using array comparative genomic hybridization (array CGH) or Single Nucleotide Polymorphism (SNP) arrays.  However, for deletions or duplications smaller than 50-100 kB, these technologies have a poor detection rate with many false positive and false negative findings unless platforms are used that target specific candidate regions. Exome analysis, on the other hand, is capable of assessing genetic variation reliably on the single base-pair level. Between both technologies, there is a grey zone of structural genomic variants that are difficult to detect; CNVs smaller than 50 kB are often difficult to assess, and the extent and pathogenic role of these small CNVs is unclear. Now, a recent paper in the American Journal of Human Genetics manages to detect small CNVs through exome data. Their analysis in patients with autism, parents, and unaffected siblings suggests a contribution of small inherited CNVs to the overall autism risk. Continue reading