Wessex Clinical Genetics Service, Princess Anne Hospital, University Hospital Southampton NHS Foundation Trust, Coxford Rd, Southampton SO165YA, UK.
Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
Am J Hum Genet. 2022 Jul 7;109(7):1217-1241. doi: 10.1016/j.ajhg.2022.05.009. Epub 2022 Jun 7.
GRIA1 encodes the GluA1 subunit of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors, which are ligand-gated ion channels that act as excitatory receptors for the neurotransmitter L-glutamate (Glu). AMPA receptors (AMPARs) are homo- or heteromeric protein complexes with four subunits, each encoded by different genes, GRIA1 to GRIA4. Although GluA1-containing AMPARs have a crucial role in brain function, the human phenotype associated with deleterious GRIA1 sequence variants has not been established. Subjects with de novo missense and nonsense GRIA1 variants were identified through international collaboration. Detailed phenotypic and genetic assessments of the subjects were carried out and the pathogenicity of the variants was evaluated in vitro to characterize changes in AMPAR function and expression. In addition, two Xenopus gria1 CRISPR-Cas9 F models were established to characterize the in vivo consequences. Seven unrelated individuals with rare GRIA1 variants were identified. One individual carried a homozygous nonsense variant (p.Arg377Ter), and six had heterozygous missense variations (p.Arg345Gln, p.Ala636Thr, p.Ile627Thr, and p.Gly745Asp), of which the p.Ala636Thr variant was recurrent in three individuals. The cohort revealed subjects to have a recurrent neurodevelopmental disorder mostly affecting cognition and speech. Functional evaluation of major GluA1-containing AMPAR subtypes carrying the GRIA1 variant mutations showed that three of the four missense variants profoundly perturb receptor function. The homozygous stop-gain variant completely destroys the expression of GluA1-containing AMPARs. The Xenopus gria1 models show transient motor deficits, an intermittent seizure phenotype, and a significant impairment to working memory in mutants. These data support a developmental disorder caused by both heterozygous and homozygous variants in GRIA1 affecting AMPAR function.
GRIA1 编码 α-氨基-3-羟基-5-甲基-4-异恶唑丙酸 (AMPA) 受体的 GluA1 亚基，AMPA 受体是配体门控离子通道，作为神经递质 L-谷氨酸 (Glu) 的兴奋性受体。AMPA 受体 (AMPAR) 是由不同基因 GRIA1 至 GRIA4 编码的同型或异型蛋白复合物。虽然含有 GluA1 的 AMPAR 在大脑功能中起着至关重要的作用，但与有害 GRIA1 序列变异相关的人类表型尚未确定。通过国际合作鉴定出具有从头错义和无义 GRIA1 变异的受试者。对受试者进行了详细的表型和遗传评估，并在体外评估了变异的致病性，以表征 AMPAR 功能和表达的变化。此外，建立了两个 Xenopus gria1 CRISPR-Cas9 F 模型来表征体内后果。鉴定出 7 名具有罕见 GRIA1 变异的无关个体。一名个体携带纯合无义变异 (p.Arg377Ter)，6 名个体具有杂合错义变异 (p.Arg345Gln、p.Ala636Thr、p.Ile627Thr 和 p.Gly745Asp)，其中 p.Ala636Thr 变异在 3 名个体中反复出现。该队列揭示了受试者存在一种复发性神经发育障碍，主要影响认知和言语。携带 GRIA1 变异突变的主要 GluA1 包含的 AMPAR 亚型的功能评估表明，四个错义变异中的三个严重扰乱受体功能。纯合终止变异完全破坏了含 GluA1 的 AMPAR 的表达。Xenopus gria1 模型显示出短暂的运动缺陷、间歇性癫痫表型以及突变体对工作记忆的显著损害。这些数据支持由 GRIA1 中的杂合和纯合变异引起的发育障碍，影响 AMPAR 功能。
