Objective:To describe young monozy gotic twin sisters with fundus albipunctatus(a type of autosomal recessive sta-tionary night blindness caused by mu tations of the 11-cis retinol dehydrogenase geneRDH5)associated with cone dystrophy,previously reported in e lderly men.Methods:Ophthalmologic examinations were p erformed,and the RDH5gene was analyzed by direct genomic sequencing.Results:Twin 23-year-old sisters with high myopic refrac-tive errors of approximately -13dio pters were diagnosed as having fundus albipunctatus.Their photopic electroretino-graphic responses were markedly red uced,and cone dys-trophy was diagnosed.One twin had ma cular degeneration with reduced best-corrected visual acuity,while the other twin had normal maculae with good vis ual acuity.A com-pound heterozygous mutation,Val132Met and Arg280His,in the RDH5gene was found in both sisters.Conclusions:Cone dystrophy can be present in pati ents with fundus al-bipunctatus,not only elderly men bu t also young women.The clinical severity differed betw een monozygotic twins with fundus albipunctatus and cone d ystrophy.Clinical Relevance:The patients sex is not critical for the presence of cone dystrophy in patients with fu ndus albipunctatus.The discordant findings in the twins indicate that factors other than genetics influenced the p henotype. Objective: To describe young monozygotic twin sisters with fundus albipunctatus (a type of autosomal recessive sta-tionary night blindness caused by mu tations of the 11-cis retinol dehydrogenase gene RDH5) associated with cone dystrophy, previously reported in e lderly men. Methods: Ophthalmologic examinations were p erformed, and the RDH5 gene was analyzed by direct genomic sequencing. Results: Twin 23-year-old sisters with high myopic refrac-tive errors of approximately -13dio pters were diagnosed as having fundus albipunctatus.Their photopic electroretino-graphic responses were markedly red uced, and cone dys-trophy was diagnosed. One twin had ma cular degeneration with reduced best-corrected visual acuity, while the other twin had normal maculae with good vis ual acuity. A com-pound heterozygous mutation, Val132 Met and Arg280 His , in the RDH5 gene was found in both sisters. Conclusions: Cone dystrophy can be present in pati ents with fundus al-bipunctatus, not only elderly men bu t also young women. Th e clinical severity differed betwen monozygotic twins with fundus albipunctatus and cone dystrophy. Clinical Relevance: The patient’s sex is not critical for the presence of cone dystrophy in patients with fu ndus albipunctatus. discordant findings in the twins indicate that factors other than genetics influenced the p henotype.