GNAT1 gene

• Overview
• Retinitis pigmentosa
• Additional information
• References

Overview

Gene (OMIM No.)	GNAT1 (#139330)
Function of gene/protein	Protein: G-protein alpha subunit of rod transducin Involved in rod phototransduction Upon light stimulus, the activated protein initiates downstream reactions which eventually leads to photoreceptor hyperpolarisation
Clinical phenotype (OMIM phenotype no.)	Congenital stationary night blindness, autosomal dominant 3 (#610444) Congenital stationary night blindness, type 1G (#616389) Late-onset autosomal recessive retinitis pigmentosa (RP)
Inheritance	Autosomal recessive Autosomal dominant
Ocular features	Normal fundus in CSNB Typical RP features +/- perifoveal atrophy
Visual function	CSNB Nyctalopia from early infancy VA and colour vision unaffected Myopia Autosomal recessive RP Nyctalopia from the 2nd decade of life Progressive VF loss VA variable ranging from 6/6 (80 years old) to 6/24 (32 years old)
Systemic features	No extraocular anomalies reported
Key investigations	CSNB ERG: Riggs type with reduced a- and b-wave amplitude under scotopic conditions RP ERG: absent responses/severe rod-cone dystrophy FAF: Hypo-AF in areas of atrophy OCT: Preserved foveal EZ in one case to marked thinning of the foveal outer retinal layers in another case
Molecular diagnosis	Next generation sequencing Targeted gene panels (retinal) Whole exome sequencing Whole genome sequencing
Management	Ocular Management of RP
Therapies under research	None at present
Further information	Medline Plus

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Additional information

GNAT1 missense variants are associated with stationary disease while nonsense variants are associated with progressive retinopathy ^[8].

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References

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