MERTK gene

• Overview
• Retinitis pigmentosa
• Additional information
• References

Overview

Gene (OMIM No.)	MERTK (#604705)
Function of gene/protein	Protein: MER proto-oncogene, tyrosine kinase Regulates many physiological processes such as cell survival, migration, differentiation and phagocytosis of apoptotic cells Regulates RPE phagocytosis of shed photoreceptor outer segments
Clinical phenotype (OMIM phenotype no.)	Autosomal recessive retinitis pigmentosa: Retinitis pigmentosa 38 (#613862)
Inheritance	Autosomal recessive
Signs for AR-RP	Optic disc pallor Vessel attenuation Scarce bone spicule pigmentation in the mid-periphery Subtle white dots/RPE mottling in the periphery in some cases Early macular involvement with a range of abnormalities RPE mottling, and yellowish-white deposits, bull’s eye maculopathy and macular atrophy) Posterior sub-capsular cataract
Visual function	Nyctalopia within the first two decades of life VF may be preserved into the 2nd decade but tend to deteriorate gradually thereafter Some patients have relatively preserved BCVA (as good as 6/6) in the 2nd decade; progressive decline over time with most reaching PL vision by the 6th decade Dyschromatopsia
Systemic features	No extraocular features reported
Key investigations	Full field ERG: rod-cone dystrophy initially; unrecordable or significantly reduced rod and cone responses in later stages Pattern ERG: Early loss of responses FAF: Foveal hyper AF surrounded by a ring of decreased AF or atrophic patches centrally in advanced stages Multifocal fine hyper-AF dots in the posterior pole can be observed in younger patients OCT: Severe ONL thinning with disruption/loss of EZ and ELM; hyper-reflective dots above the RPE/Bruch’s complex may correspond to some of the hyper-AF dots but this finding is not specific to MERTK-retinopathy
Molecular diagnosis	Next generation sequencing Targeted gene panels (retinal) Whole exome sequencing Whole genome sequencing
Management	Management of RP
Therapies under research	Gene therapy (NCT 01482195, phase 1) 2-year data reported by (Ghazi et al)
Further information	OMIM

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Additional information

Pathogenic mutations in MERTK account for 2-3% of AR-RP cases.^[1-3]

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References

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