Unilateral BEST1-Associated Retinopathy.

PURPOSE: To describe a series of patients with molecularly confirmed mutation in BEST1 causing Best disease but with unilateral clinical manifestation. DESIGN: Retrospective observational case series. SETTING: Moorfields Eye Hospital and Great Ormond Street Hospital, London (United Kingdom). PATIENTS: Five patients (10 eyes) with uniocular manifestation of BEST1 mutation causing Best disease were ascertained retrospectively from the clinical and genetic databases. MAIN OUTCOME MEASURES: Patients had full ophthalmologic examination, color fundus photography, fundus autofluorescence imaging, spectral-domain optical coherence tomography, and detailed electrophysiological assessment. Genetic testing was performed. RESULTS: All cases had a clinical appearance typical of and consistent with Best disease at various stages, except that the presentation was unilateral. The reduced electrooculogram light rise was bilateral and in the context of normal electroretinograms therefore indicates generalized dysfunction at the level of the retinal pigment epithelium. CONCLUSIONS: Mutation in BEST1 has variable penetrance and expressivity, and can be uniocular. The clinical and electrophysiological features described assist targeted mutational screening and alert to the potential diagnosis even when there is an atypical unilateral presentation.