Early Repolarization Syndrome, Epilepsy and Atrial Fibrillation in a young girl with novel KCND3 mutation managed with quinidine

Gene mutations in comorbidity of epilepsy and arrhythmia

Epilepsy is one of the most common neurological disorders, and sudden unexpected death in epilepsy (SUDEP) is the most severe outcome of refractory epilepsy. Arrhythmia is one of the heterogeneous factors in the pathophysiological mechanism of SUDEP with a high incidence in patients with refractory epilepsy, increasing the risk of premature death. The gene co-expressed in the brain and heart is supposed to be the genetic basis between epilepsy and arrhythmia, among which the gene encoding ion channel contributes to the prevalence of "cardiocerebral channelopathy" theory. Nevertheless, this theory could only explain the molecular mechanism of comorbid arrhythmia in part of patients with epilepsy (PWE). Therefore, we summarized the mutant genes that can induce comorbidity of epilepsy and arrhythmia and the possible corresponding treatments. These variants involved the genes encoding sodium, potassium, calcium and HCN channels, as well as some non-ion channel coding genes such as CHD4, PKP2, FHF1, GNB5, and mitochondrial genes. The relationship between genotype and clinical phenotype was not simple linear. Indeed, genes co-expressed in the brain and heart could independently induce epilepsy and/or arrhythmia. Mutant genes in brain could affect cardiac rhythm through central or peripheral regulation, while in the heart it could also affect cerebral electrical activity by changing the hemodynamics or internal environment. Analysis of mutations in comorbidity of epilepsy and arrhythmia could refine and expand the theory of "cardiocerebral channelopathy" and provide new insights for risk stratification of premature death and corresponding precision therapy in PWE.

Association of Cardiac Electrical Disorders With KCND3 Gene Mutation

Globally, cardiac channelopathies leading to electrical disorders are responsible for a significant number of sudden cardiac deaths without structural heart disease. Many genes encoding different ion channels in the heart were identified and their impairment was found to be associated with life-threatening cardiac abnormalities. KCND3, one of the genes expressed both in the heart and brain, is reported to have an association with Brugada syndrome, early-onset atrial fibrillation, early repolarization syndrome, and sudden unexplained death syndrome. KCND3 genetic screening could be a promising tool for functional studies for an understanding of the pathogenesis and genetic determinants of the above-mentioned electrical disorders.