Identifying core phenotypes – epilepsy, ID and recurrent microdeletions

Triad. There are three microdeletions in particular that increase the risk for the Idiopathic/Genetic Generalized Epilepsies (IGE/GGE). This triad includes microdeletions at 15q13.3, 16p13.11 and 15q11.2, which are hotspot deletions arising from the particular architecture of the human genome. While the association of these microdeletions with epilepsy and other neurodevelopmental disorders including autism, intellectual disability and schizophrenia is well established, the core phenotype of these variants remains elusive, including the question whether such a core phenotype actually exists. In a recent paper in Neurology, Mullen and collaborators zoom in on a possible core phenotype of these microdeletions. The authors investigate a phenotype in which these microdeletions are particularly enriched: generalized epilepsy with intellectual disability. Continue reading

“Meta-channelopathies” – RBFOX1 deletions and human epilepsy

Man is built to seize. When Hughlings Jackson made this famous comment pertaining to the inherent hyperexcitability of the human brain in response to a wide range of different stimuli, he probably didn’t anticipate the mechanisms of splicing regulation. Our CNS is actively protected from hyperexcitability through directed splicing of ion channel mRNA. Now, a recent study in Epilepsia finds that these mechanisms may be dysfunctional in human epilepsy. Continue reading

Close encounters of the third kind – rare genetic variants in families

A new beast. Rare genetic variants probably account for a significant fraction of the genetic liability to many common and rare disorders. Rare variants occupy the liability space between monogenic variants and common genetic variants. Their existence has often been postulated, and genetic investigations looking at copy number variants have elucidated some examples of rare variants. These rare variants appear to carry particular properties that are quite unexpected including the way that these variants run in families. Now, in a recent paper in the European Journal of Human Genetics, we have developed a model of the way rare variants behave in families. And there is a lot of misbehaving. Continue reading