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Hum Mol Genet. 2017 Mar 15;26(6):1078-1086. doi: 10.1093/hmg/ddx018.

Novel GNB1 mutations disrupt assembly and function of G protein heterotrimers and cause global developmental delay in humans.

Author information

1
Institute of Neurogenetics, University of Lübeck, 23538?Lübeck, Germany.
2
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
3
Centogene AG, 18057 Rostock, Germany.
4
Neurology Clinic, University of Belgrade, 11000 Belgrade, Serbia.
5
Institut fur Humangenetik, Universität zu Lübeck, 23538 Lübeck, Germany.
6
Centre for Human Molecular Genetics, Faculty of Biology, University of Belgrade, Belgrade, Serbia.

Abstract

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.

PMID:
28087732
PMCID:
PMC6075543
DOI:
10.1093/hmg/ddx018
[Indexed for MEDLINE]
Free PMC Article

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