[Best's disease. Overview of pathology and its causes].

Best's disease is a hereditary affection with reduced penetrance and juvenile onset. The fundus may be unremarkable or present various stages up to scarring of the macula. Histopathology of advanced stages discloses deposits of lipofuscin on Bruch's membrane, the innermost layer of which is the basal membrane of the retinal pigment epithelium (RPE). The deposits correlate with lipofuscin and melanofuscin granulae in the RPE. Photoreceptors correlating with the lesions have lost their outer segments and the RPE as well as the photoreceptors appear edematous. Loss of photoreceptor function does not necessarily follow progression of fundus appearance. Loss of function usually correlates with a reduced Arden ratio of the electro-oculogram even in the absence of funduscopic changes.Best's disease is caused by mutations in VMD2 (hBEST1). Bestrophin, the gene product of hBEST1, is a regulatory part of a Ca(2+) channel or a Ca(2+)-dependent Cl(-)channel. In this paper the relevant data on clinical and genetic pathology are summarized and evaluated.