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Rodrigo Matsui, Salvador Lopez-Rubio, Oscar Chacon, Juan Carlos Zenteno Ruiz; Clinical characterization of an uncommon ABCA4 mutation in Mexican Population. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3222.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the clinical, functional, and OCT retinal imaging phenotypes associated with the uncommon p.A1773V ABCA4 mutation in Mexican population.
A total of 10 molecularly diagnosed STGD patients were included in the study. Of them, 9 were homozygous and 1 was heterozygous for the p.A1773V mutation in ABCA4. Patients underwent a complete eye examination including best-corrected visual acuity, electroretinography (ERG), and Goldmann kinetic visual fields. Full-field ERGs were performed in all the patients using the ISCEV standard stimuli. Retinal cross-sections were obtained with SD- optical coherence tomography. A 9-mm line scan along the horizontal meridian crossing the fovea was used for all the patients. Quantitation of ONL thickness and eccentricity of ellipsoid zone were measured. SW-AF (488 nm) was performed in the "high-speed" mode. Quantitative analyses of hypofluorescent central areas were manually measured.
The patients ranged in age from 9 to 32 years (average, 24; SD, 8.0 years) when first diagnosed. Best-corrected visual acuities ranged from 20/200 to 4/200 in the eye with best vision at first examination. A common fundoscopic finding in 6 affected individuals from 4 different families was well demarcated pigmented lesions in the mid and far peripheral retina. The most common pattern of visual field abnormality was the presence of an absolute scotoma involving the central 5 degrees of vision with normal extent of peripheral visual field. The majority of the patients (9/10) showed more preservation of peripheral rod function in comparison with peripheral cone function by ERG. In vivo microstructure by SD-OCT showed central retinal thinning and loss of photoreceptors with variable degrees of extension. Abnormal autofluorescence was characterized by a localized central area of decreased autofluorescence surrounded by a heterogeneous background of high or low autofluorescence areas extending anterior to the vascular arcades.
We describe the retinal phenotype associated with a founder mutation in ABCA4 in a subgroup of STGD patients from Mexico. Population genetic studies for known mutations to determine allele frequencies and their regional distributions could lead to more precise recommendations for genetic testing and could also help to define a better genotype-phenotype correlation in the group of ABCA4-linked retinal dystrophies.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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