Ocular manifestations of metabolic disorders

Major advances in the molecular basis of oculocutaneous and ocular albinism have been published. In addition to mutations of the P gene, some patients, with so-called autosomal recessive ocular albinism, were found to have a tyrosinase gene mutation in one allele and a nucleotide substitution of the same gene, which was considered as a polymorphism, in another allele. This finding has great impact on the diagnosis and genetic counseling of albinism. Flash visually evoked potentials may be a useful tool to show the asymmetry pattern in albino patients especially in infants. Some reports suggested that there may be an overlap between corneal amyloidosis and other forms of corneal dystrophy. Lattice dystrophy, granular dystrophy, and Avellino (granular-lattice) dystrophy were mapped on the same locus of chromosome 5q. Histopathologic findings supported that these different phenotypes were derived from defects of the same gene. Gelatinous droplike dystrophy and spheroidal band-shaped degeneration were also suggested to be allelic disorders by clinical and histopathological findings.