Clinical and genetic characteristics of epilepsy of infancy with migrating focal seizures in Chinese children.

OBJECTIVE Epilepsy of infancy with migrating focal seizures (EIMFS) is a rare and severe developmental epileptic encephalopathy. The aim of this study was to improve our understanding of EIMFS by using phenotype-genotype correlation. METHODS We recruited, performed clinical genetic testing, and summarized the clinical features and genetic characteristics in five patients with EIMFS in China. RESULTS The five recruited patients included 2 males and 3 females. The median age of seizure onset was 2 months (range, day 3 to 3 months). All patients exhibited the characteristics of clinically migrating focal motor (tonic or clonic) seizures. Typical migrating ictal electrical patterns were found in 1 patient; the remaining four patients presented with overlapping seizures with different areas of ictal onset in differing hemispheres. All the patients had the associated variants, including KCNT1, SCN1A, SCN2A, TBC1D24 and ALG1. All patients received two or more antiseizure medications, and 1 patient became seizure-free, 1 reported >75 % seizure reduction, 2 reported >50 % seizure reduction, and 1 patient showed no improvement. Varying degrees of psychomotor developmental delays were observed in all patients. CONCLUSIONS The course of EIMFS could be related to the type of gene variant present, and different genes may have specific clinical features. Larger cohorts are required to elucidate such potential phenotype-genotype correlations.