PURPOSE: GRIA3, encoding subunit 3 of glutamate ionotropic AMPA receptor, is 
associated with X-linked intellectual disability (ID), dysmorphic features, and 
non-syndromic epilepsy. We aimed to characterize electro-clinical features of 
patients with GRIA3 variants.
METHODS: We report a patient carrying a hemizygous missense variant c.2359 G > A 
(p.Glu787Lys) inGRIA3 gene. Following a literature search, we also reviewed 
clinical, electrophysiological, radiological, and genetic features of 19 
patients with GRIA3 mutations.
RESULTS: This 26-month-old boy had developmental delay, early onset refractory 
myoclonic epilepsy, and non-convulsive refractory status epilepticus. In 
published reports, epilepsy was in 6 of 19 patients carrying different 
genotypes, though epilepsy and electroencephalogram features were not completely 
defined. Out of the 6 patients, one presented with generalized tonic-clonic 
seizures, two with myoclonic and clonic events (one also presented with 
epileptic spasms), and one with atypical absences and myoclonic jerks. 
Information on type of epilepsy was unavailable for 3 cases. Epilepsy onset was 
early in life and there was potential tendency for myoclonic/clonic events. The 
epilepsy was difficult to treat and prognosis is poor. Severity of ID ranged 
from mild to severe and was variably associated with bipolar affective disorder 
and autistic spectrum disorders. Other neurological features included hypotonia, 
asthenic body habitus with poor muscle bulk, and hyporeflexia.
CONCLUSION: Our report expands knowledge on the electro-clinical and molecular 
spectrum of GRIA3 variants. Larger investigations will better define the 
prevalence of epilepsy, the epileptic phenotype, and syndromic features 
underlying GRIA3 variants.