CLINICAL FEATURES OF MERTK -RELATED RETINOPATHY.

PURPOSE: Biallelic pathogenic variants in MER tyrosine kinase ( MERTK ) result in a retinopathy that is of interest because gene therapy animal models have been promising. The purpose of this report is to characterize the condition in a cohort from the United Arab Emirates.

METHODS

Retrospective cases series (2016-2023, inclusive).

RESULTS

Nine families (19 affected patients) were identified. Juvenile rod-cone dystrophy with early macular involvement was the recurrent phenotype. Asymmetric visual acuity related to central macular atrophy was common after 10 years old (11/17 patients). Visual acuity was 20/70 or worse in at least one eye after 17 years old in all patients except one. Most patients had disk drusen (14/19) and myopia (16/19). Genetic testing revealed one of three homozygous pathogenic variants (NM_006343.3): c.2214del; p.Cys738Trpfs*32 (7 families, 14 patients), c.2262C>G; p.Tyr754* (1 family, 4 patients), and c.2020A>G; p.Met674Val (1 family, 1 patient).

CONCLUSION

In MERTK -related retinopathy, significant visual acuity loss usually occurs by the teenage years and is often asymmetric. Disk drusen and myopia are recurrent. In the United Arab Emirates, a specific variant underlies most cases (c.2214del; p.Cys738Trpfs*32) and likely represents founder effect.