Lohmann Katja, Masuho Ikuo, Patil Dipak N, Baumann Hauke, Hebert Eva, Steinrücke Sofia, Trujillano Daniel, Skamangas Nickolas K, Dobricic Valerija, Hüning Irina, Gillessen-Kaesbach Gabriele, Westenberger Ana, Savic-Pavicevic Dusanka, Münchau Alexander, Oprea Gabriela, Klein Christine, Rolfs Arndt, Martemyanov Kirill A
Institute of Neurogenetics, University of Lübeck, 23538?Lübeck, Germany.
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
Hum Mol Genet. 2017 Mar 15;26(6):1078-1086. doi: 10.1093/hmg/ddx018.
Global developmental delay (GDD), often accompanied by intellectual disability, seizures and other features is a severe, clinically and genetically highly heterogeneous childhood-onset disorder. In cases where genetic causes have been identified, de novo mutations in neuronally expressed genes are a common scenario. These mutations can be best identified by exome sequencing of parent-offspring trios. De novo mutations in the guanine nucleotide-binding protein, beta 1 (GNB1) gene, encoding the Gβ1 subunit of heterotrimeric G proteins, have recently been identified as a novel genetic cause of GDD. Using exome sequencing, we identified 14 different novel variants (2 splice site, 2 frameshift and 10 missense changes) in GNB1 in 16 pediatric patients. One mutation (R96L) was recurrently found in three ethnically diverse families with an autosomal dominant mode of inheritance. Ten variants occurred de novo in the patients. Missense changes were functionally tested for their pathogenicity by assaying the impact on complex formation with Gγ and resultant mutant Gβγ with Gα. Signaling properties of G protein complexes carrying mutant Gβ1 subunits were further analyzed by their ability to couple to dopamine D1R receptors by real-time bioluminescence resonance energy transfer (BRET) assays. These studies revealed altered functionality of the missense mutations R52G, G64V, A92T, P94S, P96L, A106T and D118G but not for L30F, H91R and K337Q. In conclusion, we demonstrate a pathogenic role of de novo and autosomal dominant mutations in GNB1 as a cause of GDD and provide insights how perturbation in heterotrimeric G protein function contributes to the disease.
全球发育迟缓（GDD）通常伴有智力残疾、癫痫发作和其他特征，是一种严重的、临床和遗传高度异质性的儿童期起病疾病。在已确定遗传病因的病例中，神经元表达基因的新发突变是常见情况。这些突变通过亲子三联体的外显子组测序能得到最佳识别。鸟嘌呤核苷酸结合蛋白β1（GNB1）基因的新发突变，该基因编码异源三聚体G蛋白的Gβ1亚基，最近已被确定为GDD的一种新的遗传病因。通过外显子组测序，我们在16例儿科患者的GNB1中鉴定出14种不同的新变体（2个剪接位点、2个移码突变和10个错义变化）。在三个不同种族的家庭中以常染色体显性遗传模式反复发现一个突变（R96L）。10个变体在患者中为新发突变。通过检测对与Gγ形成复合物以及与Gα形成突变体Gβγ的影响，对错义变化的致病性进行了功能测试。通过实时生物发光共振能量转移（BRET）分析携带突变Gβ1亚基的G蛋白复合物与多巴胺D1R受体偶联的能力，进一步分析其信号特性。这些研究揭示了错义突变R52G、G64V、A92T、P94S、P96L、A106T和D118G的功能改变，但L30F、H91R和K337Q没有。总之，我们证明了GNB1中的新发和常染色体显性突变作为GDD病因的致病作用，并提供了关于异源三聚体G蛋白功能扰动如何导致该疾病的见解。
