Fundus Albipunctatus: A Novel Mutation

Background: The aim of this paper is to describe a patient with fundus albipunctatus from Africa who is developing a cone dystrophy with a new mutation in RDH5. Methods: A 24-year-old female from Burundi presented with difficulty to adapt to darkness after being in the light since the age of 9 years old. The clinical history, visual field, electroretinogram (ERG), dark adaptation test, spectral-domain optical coherence tomography (SD-OCT); fundus autofluorescence (FAF) and polymerase chain reaction (PCR) plus DNA analysis (by Sanger sequencing) were performed. Results: Fundus examination revealed scattered, homogenous, yellow-white dots throughout both fundi. OCT showed extrafoveal numerous well-demarcated homogenous dome-shaped lesions originating in the RPE. FAF showed a lack of autofluorescence (AF). Electroretinogram of the cone and the mixed rod-cone system had a normal morphology but with a significant decrease in the a and b wave amplitudes and a delayed peak time. The rod-mediated ERG was non-detectable. However, after a prolonged (3-hour) period of dark adaptation, the rod-mediated ERG was detectable and the b-wave reached 48% of normal value. The DNA analysis and sequencing of RDH5 revealed a homozygous c. 524-526delACT mutation, leading to a protein change of p.Tyr175del, which has not been reported before. The cone ERG results, strongly suggest that she is developing a cone dystrophy, despite the fact that she is asymptomatic and still maintains 20/20 vision and normal color discrimination. Conclusion: We identified a new deletion in RDH5 responsible for fundus albipunctatus with a progressive cone dystrophy; c. 524-526delACT in a patient from Burundi.