RRC ID 70782
Author Hamanaka K, Miyoshi K, Sun JH, Hamada K, Komatsubara T, Saida K, Tsuchida N, Uchiyama Y, Fujita A, Mizuguchi T, Gerard B, Bayat A, Rinaldi B, Kato M, Tohyama J, Ogata K, Shi YS, Saito K, Miyatake S, Matsumoto N.
Title Amelioration of a neurodevelopmental disorder by carbamazepine in a case having a gain-of-function GRIA3 variant.
Journal Hum Genet
Abstract GRIA3 at Xq25 encodes glutamate ionotropic receptor AMPA type 3 (GluA3), a subunit of postsynaptic glutamate-gated ion channels mediating neurotransmission. Hemizygous loss-of-function (LOF) variants in GRIA3 cause a neurodevelopmental disorder (NDD) in male individuals. Here, we report a gain-of-function (GOF) variant at GRIA3 in a male patient. We identified a hemizygous de novo missense variant in GRIA3 in a boy with an NDD: c.1844C > T (p.Ala615Val) using whole-exome sequencing. His neurological signs, such as hypertonia and hyperreflexia, were opposite to those in previous cases having LOF GRIA3 variants. His seizures and hypertonia were ameliorated by carbamazepine, inhibiting glutamate release from presynapses. Patch-clamp recordings showed that the human GluA3 mutant (p.Ala615Val) had slower desensitization and deactivation kinetics. A fly line expressing a human GluA3 mutant possessing our variant and the Lurcher variant, which makes ion channels leaky, showed developmental defects, while one expressing a mutant possessing either of them did not. Collectively, these results suggest that p.Ala615Val has GOF effects. GRIA3 GOF variants may cause an NDD phenotype distinctive from that of LOF variants, and drugs suppressing glutamatergic neurotransmission may ameliorate this phenotype. This study should help in refining the clinical management of GRIA3-related NDDs.
Volume 141(2)
Pages 283-293
Published 2022-2-1
DOI 10.1007/s00439-021-02416-7
PII 10.1007/s00439-021-02416-7
PMID 35031858
MeSH Amino Acid Substitution Animals Animals, Genetically Modified Carbamazepine / therapeutic use* Child, Preschool Drosophila melanogaster / genetics Drosophila melanogaster / metabolism Excitatory Amino Acid Antagonists / therapeutic use* Gain of Function Mutation* HEK293 Cells Humans Male Mutant Proteins / chemistry Mutant Proteins / genetics Mutant Proteins / metabolism Mutation, Missense Neurodevelopmental Disorders / drug therapy* Neurodevelopmental Disorders / genetics* Neurodevelopmental Disorders / metabolism Patch-Clamp Techniques Phenotype Receptors, AMPA / chemistry Receptors, AMPA / genetics* Receptors, AMPA / metabolism Recombinant Proteins / chemistry Recombinant Proteins / genetics Recombinant Proteins / metabolism
IF 5.743
Drosophila DGRC#108284