| A genetic macular dystrophy with characteristics of loss of central visual acuity, metamorphopsia and a decrease in the Arden ratio secondary to an egg yolk-like lesion located in the foveal or parafoveal region. Onset is in childhood and sometimes in later teenage years (5-13 years). Affected individuals have normal vision at birth. The disease then progresses through distinct stages and has characteristics of atrophy of the retinal pigment epithelium (RPE) affecting photoreceptors with impaired central visual function. In most cases, the disease is caused by mutations in BEST1 (11q12), encoding for bestrophin-1, a chloride channel expressed in RPE. A defect in this protein leads to accumulation of lipofuscin secondary to abnormal ion exchange. Inherited in an autosomal dominant manner with complete penetrance. |
