• 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 retino-choroidal 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.
Small KW, Anderson WB. Pigmented Paravenous Retinochoroidal AtrophyDiscordant Expression in Monozygotic Twins. Arch Ophthalmol. 1991;109(10):1408-1410. doi:10.1001/archopht.1991.01080100088048