RESUMEN
We studied a patient with a severe phenotype carrying two GNB5 variants: c.514delT from the unaffected heterozygous mother and c.628-6G>A from the unaffected homozygous father. Functional genomics studies showed that parents express 50% (nonsense-mediated decay, NMD) of the RNA/protein while the patient does not produce enough protein for normal development.
Asunto(s)
Subunidades beta de la Proteína de Unión al GTP , ARN , Femenino , Humanos , Alelos , ARN Mensajero/genética , Madres , Genómica , Degradación de ARNm Mediada por Codón sin Sentido , Subunidades beta de la Proteína de Unión al GTP/genéticaRESUMEN
The GRIA3 gene is located in the X chromosome and encodes for one of the subunits (iGluR3) of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), an excitatory synaptic transmission receptor present in most parts of the brain. iGluR3 dysfunction has been associated with both abnormal memory formation and learning. It has been observed in patients with different neurological and cognitive disorders, including epilepsy. Three different de novo missense variants of GRIA3 have recently been reported in patients with Developmental and Epileptic Encephalopathy (DEE). We report on a female pediatric patient with DEE whose clinical picture mimicked structural epilepsy. We give a detailed description of our patient's most important electro-clinical features. Genetic analysis revealed that the patient carried a de novo missense variant in GRIA3 (c.2359G>A; p.Glu787Lys). The p.Glu787Lys variant had previously been reported in a male pediatric patient. Additionally, we studied iGluR3 expression in the patient and control fibroblasts. We found significantly lower iGluR3 expression in the patient's fibroblasts than in controls and different responses to glutamate treatment. In summary, our report expands knowledge of GRIA3 variants affecting boys and girls, describes functional studies of these variants, and provides an extensive review of the literature concerning GRIA3 genetic variants.