We conclude that the GABRA1 (R214C) variant reduces channel activity and surface expression of mutant receptors, thereby contributing to the pathogenesis of genetic EE.
In this report, we provide a detailed clinical description of a sporadic male patient with early-onset epilepsy and epileptic encephalopathy in whom we performed complete exome sequencing (WES) and identified a GRIN2B mutation.
The first mutations identified in SLC2A1, encoding the glucose transporter type 1 (GLUT1) protein of the blood-brain barrier, were associated with severe epileptic encephalopathy.
Glucose transporter type 1 deficiency syndrome (Glut1DS) is the result of autosomal-dominant loss-of-function mutation of the glucose transporter type 1 gene (GLUT1) leading to brain energy failure and epileptic encephalopathy.
Exome sequence identified a c.320A > G ALG13 variant in a female with infantile epileptic encephalopathy with normal glycosylation and random X inactivation: Review of the literature.
Among these are GABRB3, with de novo mutations in four patients, and ALG13, with the same de novo mutation in two patients; both genes show clear statistical evidence of association with epileptic encephalopathy.
Mutations in ACTL6B, coding for a subunit of the neuron-specific chromatin remodeling complex nBAF, cause early onset severe developmental and epileptic encephalopathy with brain hypomyelination and cerebellar atrophy.
In this largest series to date on KCTD3-mutated patients, we show that biallelic loss of function mutations in KCTD3 lead to a consistent phenotype of developmental epileptic encephalopathy and abnormal cerebellum on brain imaging.
Our results support the importance of genetic testing of the CDKL5 gene in patients with early-onset epileptic encephalopathy and Rett-like features with early-onset seizures.
De novo mutations of the sodium channel gene SCN8A result in an epileptic encephalopathy with refractory seizures, developmental delay, and elevated risk of sudden death. p.Arg1872Trp is a recurrent de novo SCN8A mutation reported in 14 unrelated individuals with epileptic encephalopathy that included seizure onset in the prenatal or infantile period and severe verbal and ambulatory comorbidities.
Heterozygous inherited mutations in their principle subunits K<sub>v</sub> 7.2/KCNQ2 and K<sub>v</sub> 7.3/KCNQ3 cause benign familial neonatal epilepsy whereas patients with de novo heterozygous K<sub>v</sub> 7.2 mutations are associated with early-onset epileptic encephalopathy and neurodevelopmental disorders characterized by intellectual disability, developmental delay and autism.
We previously described the heterozygous SCN8A missense mutation p.Asn1768Asp in a child with epileptic encephalopathy that included seizures, ataxia, and sudden unexpected death in epilepsy (SUDEP).
Mutations in the cyclin-dependent kinase-like 5 (CDKL5) gene have been described in girls with Rett-like features and early-onset epileptic encephalopathy including infantile spasms.
Our report suggests that the clinical features associated with CDKL5 deletions could be implicated in Japanese patients, and that genetic testing of CDKL5, including both sequencing and deletion analyses, should be considered in girls with early-onset epileptic encephalopathy and RTT-like features.