[Developmental and epileptic encephalopathy 33 caused by <i>EEF1A2</i> gene mutation: a case report].

A boy, aged 7 months, presented with severe global developmental delay (GDD), refractory epilepsy, hypotonia, nystagmus, ocular hypertelorism, a broad nasal bridge, everted upper lip, a high palatal arch, and cryptorchidism. Genetic testing revealed a <i>de novo</i> heterozygous missense mutation of c.364G>A(p.E122K) in the <i>EEF1A2</i> gene, and finally the boy was diagnosed with autosomal dominant developmental and epileptic encephalopathy 33 caused by the <i>EEF1A2</i> gene mutation. This case report suggests that for children with unexplained infancy-onset severe to profound GDD/intellectual disability and refractory epilepsy, genetic testing for <i>EEF1A2</i> gene mutations should be considered. This is particularly important for those exhibiting hypotonia, nonverbal communication, and craniofacial deformities, to facilitate a confirmed diagnosis.