Temple-Baraitser syndrome (TBS) is a multisystem developmental disorder characterized by intellectual disability, epilepsy, and hypoplasia or aplasia of the nails of the thumb and great toe. Here we report damaging de novo mutations in KCNH1 (encoding a protein called ether à go-go, EAG1 or KV10.1), a voltage-gated potassium channel that is predominantly expressed in the central nervous system (CNS), in six individuals with TBS. Characterization of the mutant channels in both Xenopus laevis oocytes and human HEK293T cells showed a decreased threshold of activation and delayed deactivation, demonstrating that TBS-associated KCNH1 mutations lead to deleterious gain of function. Consistent with this result, we find that two mothers of children with TBS, who have epilepsy but are otherwise healthy, are low-level (10% and 27%) mosaic carriers of pathogenic KCNH1 mutations. Consistent with recent reports, this finding demonstrates that the etiology of many unresolved CNS disorders, including epilepsies, might be explained by pathogenic mosaic mutations.
Non epileptic paroxysmal events are recurrent movement disorders with acute onset and ending, which may mimic epilepsy. The duration, place, timing of the attacks, and state of conciousness may confuse pediatricians about the diagnosis of epilepsy and non epileptic paroxysmal events. The key point in the diagnosis is taking an accurate and detailed history. Wrong diagnosis can give rise to anxiety of both the family and the child, interruptions in the child's education, limitations in career planning, and irreversible damages in the long term. The diagnosis can prevent unnecessary drug use and psychological damage. This review aims to discuss the clinical findings, treatment, and differential diagnoses of non epileptic paroxysmal events, and to increase awareness about non epileptic paroxysmal events among pediatricians. (Turk Pediatri Ars 2017; 52: 59-65)
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