Mutations in phototransduction and retinal signaling genes are implicated in many retinopathies. To our knowledge, GNB3 encoding the G-protein β subunit 3 (Gβ3) has not previously been implicated in human disease.
In this brief report, whole-exome sequencing was conducted on a patient with distinct inherited retinal disease presenting in childhood, with a phenotype characterized by nystagmus, normal retinal examination, and mild disturbance of the central macula on detailed retinal imaging. This sequencing revealed a homozygous GNB3 nonsense mutation (c.124C>T; p.Arg42Ter). Whole-exome sequencing was conducted from April 2015 to July 2015.
Conclusions and Relevance
Expressed in cone photoreceptors and ON-bipolar cells, Gβ3 is essential in phototransduction and ON-bipolar cell signaling. Knockout of Gnb3 in mice results in dysfunction of cone photoreceptors and ON-bipolar cells and a naturally occurring chicken mutation leads to retinal degeneration. Identification of further affected patients may allow description of the phenotypic and genotypic spectrum of disease associated with GNB3 retinopathy.
Arno G, Holder GE, Chakarova C, Kohl S, Pontikos N, Fiorentino A, Plagnol V, Cheetham ME, Hardcastle AJ, Webster AR, Michaelides M, for the UK Inherited Retinal Disease Consortium. Recessive Retinopathy Consequent on Mutant G-Protein β Subunit 3 (GNB3). JAMA Ophthalmol. 2016;134(8):924-927. doi:10.1001/jamaophthalmol.2016.1543