EFMR, also known as early infantile epileptic encephalopathy-9 (EIEE9, OMIM# 300088), is a genetic disorder, of which the de novo or familial heterozygous variation of the PCDH19 gene (OMIM 300460) is forecasted to be the second most common cause in addition to variations of the sodium voltage-gated channel alpha subunit 1 (SCN1A) gene [2–5]. The gene discussed is PCDH19; the disease is hereditary disease.