Gene mutation analysis of 175 Chinese patients with early-onset epileptic encephalopathy.

The aim of the study is to investigate the genetic characteristics and clinical features of a cohort of Chinese patients with early-onset epileptic encephalopathies (EOEEs). Targeted next-generation sequencing (NGS), focusing on 17 genes, was performed on 175 Chinese patients with EOEEs to screen gene mutations. The mutation rate was 32% (56/175). All mutations were de novo and heterozygous, including 41 novel and 15 reported mutations. Patients with cyclin-dependent kinase-like 5 (CDKL5) gene mutation accounted for the largest proportion, 13.1% (23/175). All patients with CDKL5 mutation presented severe psychomotor developmental delay and refractory seizures. The female patients presented obvious Rett-like features, which were not observed in male patients. Potassium channel, voltage-gated KQT-like subfamily Q, member 2(KCNQ2) gene mutations were detected in 13 patients. Patients with this mutation presented with early seizure onset within the first week after birth. Valproate (VPA), levetiracetam (LEV) and topiramate (TPM) were effective in most patients. Patients with specific gene mutations presented some unique clinical features, but not always. Many genes are involved in EOEEs. Targeted NGS showed a high diagnostic yield in patients with EOEEs. These findings provide useful insights for recommending treatment of gene-associated EOEEs using antiepileptic drugs.