ANO3, SCN1A, IL10 – the new genetics of febrile seizures

GWAS. Febrile seizures affect up to 5% of all children between six months and six years and are by far the most common seizure type. While seizures in the setting of fever may be a manifestation of an underlying epilepsy, in the majority of cases, children only have one or two febrile seizures in their lifetimes. We know from twin studies that there is a strong genetic component to febrile seizures, and you might think that we would know more about the most common seizure type. However, this has not been the case until recently. The genetics of febrile seizures have been largely understudied, and we know much more about the genetics of rare epilepsies than about the genetics of febrile seizures. A recent genome-wide association study has been a game changer, highlighting a combination of fever response genes and neuronal genes in the etiology of febrile seizures. Continue reading

The zebra finch people – the genetics of stuttering in 2022

Area X. Zebra finches are a small bird species that originate from Australia and can be found all around the world. They are highly social birds and even though some zebra finches may sometimes get aggressive when defending their territory, they are generally polite if unprovoked. Seven percent of all zebra finches have interruptions and repetitions in their bird songs which is a naturally occurring variation on how zebra finches communicate. When the same phenomenon occurs in humans, it is referred to this as dysfluency or stuttering. Even though there are many myths around the causes of stuttering, developmental stuttering, the most common form of dysfluency, is a neurodevelopmental disorder with a strong genetic component as shown by twin and family studies. Dysfluency is also a phenomenon that I know extremely well given that I am a person who stutters myself. In 2013, I wrote my first blog post on the genetics of stuttering, telling the story of how my differently wired brain tripped up an epilepsy neuroimaging study. Here is a 2022 update on one of the fascinating conditions that contributes to human neurodiversity. Continue reading

A large-scale analysis of KCNQ2 variants – overcoming the functional bottleneck

KCNQ2. I have to admit we have not written about KCNQ2 for a while, which does not do justice to the role of KCNQ2 in human epilepsies. KCNQ2-related epilepsies represent some of the most common genetic epilepsies and almost exclusively present with neonatal seizures. Historically, KCNQ2 was identified in families with self-limiting neonatal seizures. Subsequently, disease-causing variants were also identified in neonatal developmental and epileptic encephalopathies (DEEs). While self-limiting epilepsies were attributed to protein-truncating variants, KCNQ2-related DEEs are attributed to dominant-negative variants. However, as in many other DEEs, this conceptual black-and-white distinction is somewhat oversimplified, and the genotype-phenotype correlation in KCNQ2-related disorders is more complex. In a recent study, we assessed a total of 81 KCNQ2 variants’ functional effects in parallel, leading to some unexpected results about the function of disease-related KCNQ2 variants. Here is what this first large-scale electrophysiological analysis of an epilepsy-related ion channel told us. Continue reading