Phenotypic variations in a family with retinal dystrophy as result of different mutations in the ABCR gene

Aims-To describe two phenotypic variations of autosomal recessive retinal d ystrophy occurring in a consanguineous family in a pseudodominant pattern, resulting from mutations in the ATP binding cassette transporter (ABCR) gen e. Methods-Patients of this family underwent an extensive ophthalmic evaluatio n, including fundus photography, fluorescein angiography, and electroretino graphy (ERG). Genetic analysis comprised sequence analysis of the retina sp ecific ABCR gene. Results-Five patients presented with decreased visual acuity in the second decade, central chorioretinal atrophy associated with a central scotoma, an d severely decreased photopic and scotopic ERG responses. This clinical pic ture, which in our opinion resembles a conerod dystrophy (CRD), was associa ted with compound heterozygosity for IVS30+ 1g -->t and IVS40+5g-->a mutati ons in the ABCR gene. The four remaining patients presented with night blin dness in the first decade because of a retinitis pigmentosa-like (RP-like) dystrophy. In addition to a pale "waxy" optic disc, attenuated retinal vess els and bone spicule deposits, a widespread chorioretinal atrophy was obser ved. The scotopic ERG was extinguished and the photopic ERG was severely di minished. Genetic analysis revealed a homozygous 5' splice mutation IVS30+1 g -->t in the ABCR gene. Conclusion-Mutations in the ABCR gene can cause clinical pictures resemblin g autosomal recessive RP and autosomal recessive CRD.