A parafoveal ring of autofluorescence is a marker of disease in a large family with autosomal dominant sector RP associated with rhodopsin gene codon 190 mutation

Purpose: to investigate the correlation between the genotype and the phenotypic pattern of fundus autofluorescence in a large family with autosomal dominant sector RP. Methods: A large Sardinian family (fig. 1) with a clinical diagnosis of autosomal dominant sector RP over at least 4 generations, was investigated genetically and clinically. Ophthalmologic examination included refraction, best visual acuity at distance, slit lamp examination, fundoscopy, fundus photography, fundus autofluorescence (SLO-HRA Heidelberg) computerized perimetry (Humphrey), microperimetry (Nidek) color vision (Lanthony Panel D 15 test) dark adaptometry (Goldmann-Weekers) and electroretinography. Results: A guanine-to-adenine mutation in the first nucleotide of rhodopsin codon 190, resulting in an aspartate-to-asparagine change, was found to be associated with the RP phenotype. Out of 40 documented members, 11 resulted to be affected. All of them showed a variably sized parafoveal ring of autofluorescence together with visual function and fundus changes typical of sector Retinitis Pigmentosa. In two young children (5 and 7 yrs), the parafoveal ring of autofluorescence was the only detectable clinical sign. The genetic analysis demonstrated that they were affected. Conclusions: A parafoveal ring of autofluorescence may predict photoreceptor degeneration in RP and represent a diagnostic clinical parameter.