Pigmented paravenous retinochoroidal atrophy. Discordant expression in monozygotic twins
K. W. Small and W. B. Anderson Jr
Department of Ophthalmology, Medical University of South Carolina, Charleston 29425-2236.
We studied a 43-year-old woman affected with pigmented paravenous
retinochoroidal atrophy and her unaffected monozygotic twin. The affected
twin had stable visual acuity (20/25), typical fundus findings, markedly
constricted visual fields, abnormal color vision, and an abnormal
electroretinogram, all consistent with pigmented paravenous retinochoroidal
atrophy. Results of examinations and studies in her twin were entirely
normal. Fingerprinting for DNA performed on the twins strongly supported
monozygosity. Our findings suggest that either our patient did not inherit
pigmented paravenous retinochoroidal atrophy or that an unusual
(nonmendelian) genetic mechanism occurred.
