Clinical and genetic characteristics of patients with type 2 early infantile epileptic encephalopathy caused by CDKL5 gene mutations

Abstract

Early infantile epileptic encephalopathies (EIEE) are a group of disorders characterized by pharmacoresistant epileptic seizures manifesting in infancy and leading to psychomotor retardation. The most common genetic variant with X-linked dominant inheritance is type 2 EIEE associated with CDKL5 gene mutations. We evaluated the prevalence of this type of EIEE among Russian patients (n = 148) with epileptic seizures manifesting in infancy and analyzed their clinical and genetic characteristics. We performed exome sequencing for all patients; 15 (10 %) of them (aged between 2 months and 5 years) were found to have CDKL5 gene mutations and were, therefore, diagnosed with type 2 EIEE. The results of correlation analysis suggest that the severity of clinical manifestations of type 2 EIEE is largely determined by the location of mutations affecting the function of the protein encoded by this gene. This is important to ensure better understanding of type 2 EIEE etiology and predict it severity in patients with different allelic variants.