Genomics meets linkage. This blog post is about family studies in epilepsy genetics. One of my tasks for the next two months is to write the “Trilateral Grant” – we were invited to submit a full proposal for a German-Israeli-Palestinian grant by the German Research Foundation (DFG) on the genetics of familial epilepsies. As keeping up our blogging schedule will be my other big task for the coming months, I thought that I could combine both and explore some topics regarding family studies on this blog. Let’s start with a sobering fact – small dominant families remain difficult to solve, not because of too little but rather too much genetic data. Continue reading
EIEE1-19. Online Mendelian Inheritance in Man (OMIM) is one of the most frequently accessed online databases for information on genetic disorders. Genes for epileptic encephalopathies are organized within a phenotypic series entitled Early Infantile Epileptic Encephalopathy (EIEE). The EIEE phenotypic series currently lists 19 genes (EIEE1-19). Let’s review the evidence for these genes as of 2014. Continue reading
Time flies by. Last week, we have had the final General Assembly of the EuroEPINOMICS project in Tuusula, Finland. All four projects of the EuroEPINOMICS consortium presented the current, ongoing projects and it’s good to hear that there are multiple publications in various stages coming up. Over the three years of the consortium, the diverse groups grew closer together. During this meeting many unpublished results were shown, including extension of studies on genes such as HCN1, CHD2, GRIN2A, GRIN2B or RBFOX1 as well as more data on epigenetics in acquired epilepsy.
Hyperpolarization. More than a quarter of a century ago, physiologists identified an electrical current in neurons and cardiac myocytes that behaved so strangely that it was called the “queer” or “funny” current: it paradoxically caused depolarization upon hyperpolarization. This current was finally named h-current and is mediated by HCN channels. The h-current has been associated with epilepsy through functional studies, but a genetic link has been elusive so far. In a recent publication in Nature Genetics, de novo mutations in HCN1 are identified in patients with early-onset epileptic encephalopathies resembling Dravet Syndrome. Continue reading
Architecture. Even though we often write about novel gene findings in the epilepsies, we assume that most epilepsies are complex genetic or polygenic. Polygenic inheritance suggests the genetic architecture is composed of multiple interacting genetic risk factors, each contributing a small proportion to the disease risk. However, when using the phrase genetic architecture, sometimes I am not quite sure what I actually mean by this. For example, how many genes are needed? This is why I wanted to build a model genetic architecture and explore what happens if we build a genetic disease solely from rare risk variants. Follow me to a brief back-of-the-envelope calculation of how this might work.
Program completed. On Sunday, we finished our EuroEPINOMICS next generation sequencing (NGS) bioinformatics meeting. After working through the command line, running scripts, and staring at black screens with white cursors, we completed our four day course by looking at the more user friendly, web-based tools that the NGS world has to offer, including Galaxy, Varbank, and Ingenuity. I think it was the general consensus among the participants that this was the bioinformatics meeting that we needed in order to understand the data that we generate and deal with on day-to-day basis. These were my favorite sound bites of our meeting. Continue reading
Lessons. Today was the first day of our bioinformatics workshop in Leuven, Belgium. We started out with some basic command line programming and eventually moved on to working with R Studio. What is this all about? It’s about getting some basic understanding of what your computer does and how your computer handles files. It’s about good data and bad data and losing the fear of the command line. We collected responses from the participants today about today’s take home messages. Continue reading
Living in Cologne is a little tough at the moment. Currently, we are in the middle of the Cologne Carnival, the world’s oldest carnival, which started in 1829. Until the upcoming Wednesday the entire city is one big festival. In addition to the 1 million Cologne citizens probably another million tourists will join. Due to this (positive) distraction I will write less than usual. However, I still consider this week’s publications noteworthy. Continue reading
Join the genome hacking league. We are preparing a EuroEPINOMICS bioinformatics workshop in Leuven and I really, really encourage you to join us, as there are handful of place left. This will be the workshop that I always wanted to attend, but never got a chance to take part in. And yes, there is a final exam, but there is a chance that you might pass it. If you’re worried, skip ahead two paragraphs.
What is missing? The catchy term “missing heritability” refers to a long-standing issue in human genetics that is particularly relevant to common diseases that are thought to have complex genetic architecture. Even though we know several thousands of risk factors for common diseases, the sum of all these risk factors only explains a small proportion of the genetic risk for disease. Where is all the remaining genetic disease risk hidden? A recent publication in PLOS Genetics suggests that known association peaks in genome-wide association studies (GWAS) may harbor more than one risk variant, turning GWAS peaks into mountain ranges. Also, this publication provides an interesting state-of-the art review on the role of common and rare variants with respect to missing heritability. Let’s turn back the clock and start with the decade-old debate on common versus rare variant models of human disease. Continue reading