<i>ZFHX3</i> variants cause childhood partial epilepsy and infantile spasms with favourable outcomes.

Abstract

The <i>ZFHX3</i> gene plays vital roles in embryonic development, cell proliferation, neuronal differentiation and neuronal death. This study aims to explore the relationship between <i>ZFHX3</i> variants and epilepsy. Whole-exome sequencing was performed in a cohort of 378 patients with partial (focal) epilepsy. A <i>Drosophila Zfh2</i> knockdown model was used to validate the association between <i>ZFHX3</i> and epilepsy. Compound heterozygous <i>ZFHX3</i> variants were identified in eight unrelated cases. The burden of <i>ZFHX3</i> variants was significantly higher in the case cohort, shown by multiple/specific statistical analyses. In <i>Zfh2</i> knockdown flies, the incidence and duration of seizure-like behaviour were significantly greater than those in the controls. The <i>Zfh2</i> knockdown flies exhibited more firing in excitatory neurons. All patients presented partial seizures. The five patients with variants in the C-terminus/N-terminus presented mild partial epilepsy. The other three patients included one who experienced frequent non-convulsive status epilepticus and two who had early spasms. These three patients had also neurodevelopmental abnormalities and were diagnosed as developmental epileptic encephalopathy (DEE), but achieved seizure-free after antiepileptic-drug treatment without adrenocorticotropic-hormone/steroids. The analyses of temporal expression (genetic dependent stages) indicated that <i>ZFHX3</i> orthologous were highly expressed in the embryonic stage and decreased dramatically after birth. <i>ZFHX3</i> is a novel causative gene of childhood partial epilepsy and DEE. The patients of infantile spasms achieved seizure-free after treatment without adrenocorticotropic-hormone/steroids implies a significance of genetic diagnosis in precise treatment. The genetic dependent stage provided an insight into the underlying mechanism of the evolutional course of illness.