The Marshall M. Parks memorial lecture: making sense of early-onset childhood retinal dystrophies--the clinical phenotype of Leber congenital amaurosis.

A correct diagnosis of the early-onset childhood retinal dystrophies requires careful clinical evaluation, the detection of suggestive or pathognomonic ophthalmoscopic clues, the use of electrophysiology to document characteristic electroretinographic findings and, in some cases, the utilisation of newer diagnostic modalities such as optical coherence tomography. Molecular diagnosis confirms the clinical diagnosis and provides the basis for possible future gene therapy. A strict definition of early-onset childhood retinal dystrophies (EOCRDs) does not exist, but inherited retinal dystrophies that are diagnosed in the first few years of life could be included under this umbrella terminology. The clinical ophthalmological manifestations of these diseases may or may not be detected at birth, and include the triad of severe vision loss, sensory nystagmus and electroretinographic abnormalities. Their clinical manifestations are light sensitivity, night blindness, fundus pigmentary changes and other psychophysical and retinal anatomic abnormalities. Diseases that could be included in the EOCRDs are Leber congenital amaurosis, achromatopsia, congenital stationary night blindness, X-linked juvenile retinoschisis, Goldmann-Favre disease and other NR2E3-related disorders, and possibly some very early-onset forms of Stargardt disease and juvenile retinitis pigmentosa. In this paper, phenotypic clues to the diagnosis of the underlying molecular defect in patients with Leber congenital amaurosis are discussed and an overview of the clinical workup of the child with a retinal dystrophy is presented. An accurate diagnosis of individual EOCRD allows a better prediction of the clinical course and the planning of possible and emerging therapies.