The rising role of synaptic transmission: the calcineurin link

Synaptic transmission. Over the last several years, pathogenic variants in multiple genes involved in synaptic transmission have been identified in early-onset epilepsies. STXBP1 and STX1B both encode components of the SNARE complex, a complicated protein complex that mediates the fusion of the plasma membrane of the presynapse and the synaptic vesicle to allow for neurotransmitter release. DNM1, encoding the dynamin-1 protein, plays an essential role in recycling synaptic vesicles back into the presynapse after neurotransmitter release. A new study by Myers and collaborators has identified several patients with de novo variants in PPP3CA, which encodes another protein involved in synaptic vesicle recycling, further highlighting the importance of synaptic transmission in the etiology of severe neurodevelopmental disorders. In the interest of full disclosure, I am also a co-author on this study. Continue reading

The tale of two planets: the expanding spectrum of STXBP1

Intergalactic, planetary. At the end of last year, I gave a presentation on epilepsy genetics for epilepsy surgeons. Having worked in presurgical epilepsy monitoring myself for some time, I could not help realizing that the fields of epilepsy surgery and epilepsy genetics are quite distinct. Both fields use different terminologies and different concepts and virtually represent parallel worlds. In the vast majority of cases, this does not really matter as there is little overlap between the patients undergoing epilepsy monitoring for later surgery and patients where a genetic etiology is assumed. In a recent paper in Epilepsia, the case of a patient with an STXBP1 mutation is presented who successfully underwent epilepsy surgery. So who is right when both fields collide while treating a single patient? Continue reading