The multiplicity of underlying genetic defects in childhood retinal dystrophies has become evident in the last two decades. A traditional clinical diagnostic label is easy to assign when the phenotype is clear-cut and matches the original delineation of the dystrophy; this continues to be feasible in most cases, but may be quite difficult in the absence of a molecular diagnosis, especially when the phenotype is on the atypical end of a spectrum. Leber congenital amaurosis (LCA), congenital stationary night blindness (CSNB), achromatopsia, and Stargardt disease are examples of conditions where these terminological conundrums arise.

Because of the limited signs and symptoms of retinal dystrophies, it is inevitable that some distinct genetically defined conditions will …