Early-onset neurodegeneration in the human retina can lead to Leber congenital amaurosis (LCA), the most severe human form of inherited photoreceptor-neuron degeneration resulting in congenital blindness, with an incidence of approximately 1 in 80,000 (summary by Koenekoop et al., 2012). NMNAT1 mutations have been observed to cause severe and rapidly progressive macular degeneration, leading to severe central atrophy with an appearance of congenital macular coloboma in the neonatal period, as well as an unusual early-onset atrophy of the optic nerve (Perrault et al., 2012). Some patients present with later onset and milder phenotype than typical LCA (Kumaran et al., 2021). For a general discussion of the phenotypic and genetic heterogeneity in Leber congenital amaurosis, see LCA1 (204000).

The appearance of yellow/white crystalline-like (hence the name) spots in the retina and thickening of the peripheral part of the vitreous.

Retinitis pigmentosa-93 (RP93) is characterized by mild to moderate rod-cone dystrophy with onset in the second or third decade of life. Patients have constricted visual fields with macular sparing and show mildly reduced visual acuity with mild to high myopia (Mejecase et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of retinitis pigmentosa, see 268000.