Rub epilepsy in an infant with Turner syndrome

The Transcription Factor Shox2 Shapes Neuron Firing Properties and Suppresses Seizures by Regulation of Key Ion Channels in Thalamocortical Neurons

Thalamocortical neurons (TCNs) play a critical role in the maintenance of thalamocortical oscillations, dysregulation of which can result in certain types of seizures. Precise control over firing rates of TCNs is foundational to these oscillations, yet the transcriptional mechanisms that constrain these firing rates remain elusive. We hypothesized that Shox2 is a transcriptional regulator of ion channels important for TCN function and that loss of Shox2 alters firing frequency and activity, ultimately perturbing thalamocortical oscillations into an epilepsy-prone state. In this study, we used RNA sequencing and quantitative PCR of control and Shox2 knockout mice to determine Shox2-affected genes and revealed a network of ion channel genes important for neuronal firing properties. Protein regulation was confirmed by Western blotting, and electrophysiological recordings showed that Shox2 KO impacted the firing properties of a subpopulation of TCNs. Computational modeling showed that disruption of these conductances in a manner similar to Shox2's effects modulated frequency of oscillations and could convert sleep spindles to near spike and wave activity, which are a hallmark for absence epilepsy. Finally, Shox2 KO mice were more susceptible to pilocarpine-induced seizures. Overall, these results reveal Shox2 as a transcription factor important for TCN function in adult mouse thalamus.

Turner Syndrome Associated With Refractory Seizures and Intellectual Disability: A Case Study

Turner syndrome (TS) is the most frequent sex abnormality in women. The physical features include short stature, webbing of the neck, and gonadal dysgenesis. Typically, patients with Turner syndrome exhibit no intellectual disability, and a few cases of TS have been associated with epilepsy. Herein, we present a case of TS with intractable epilepsy. The patient presented with global developmental delay at the age of two and karyotyping revealed mosaicism [45, X/46, X del (X) (q21.1)]. At the age of seven, she had generalized tonic epilepsy as well as several focal-onset seizures. She developed daily seizures, which were refractory to several antiepileptic drugs. Interictal electroencephalography (EEG) revealed multifocal spikes, and ictal EEG revealed shifting foci. She visited our hospital at the age of 13. Her peripheral white blood cells G-band and fluorescence in situ hybridization (FISH) method chromosome with cheek swab examinations revealed 45, X. Her peripheral white blood cell mosaic pattern may have disappeared over time or become indetectable. We treated her with clobazam, and then lamotrigine and valproic acid combination therapy, which resulted in a reduction in the frequency of seizures by approximately 50%. Epilepsy and intellectual disability in this case may be due to the mosaic deletion at Xq21.1. Further analysis of similar cases may provide valuable information for effective therapeutic strategies.