Department of Molecular, Cellular and Developmental Biology, Howard
Hughes Medical Institute, University of Colorado, Boulder, USA.
Ophthalmic Genet. 1999 Jun;20(2):69-70
Cone-rod dystrophy (CORD) and Stargardt disease (STGD) are two hereditary
retinal dystrophies with similarities to age-related macular
degeneration. Cone-rod dystrophies are a group of degenerative disorders
resulting in decreased visual acuity and color vision, attenuated
electroretinographic (ERG) responses, and atrophic macular lesions. Autosomal
dominant, autosomal recessive, and X-linked forms of cone-rod
dystrophy have been reported. Stargardt disease is characterized by reduced
visual acuity, atrophic macular changes, prominent 'flavimaculatus
flecks' in the pigment epithelium of the posterior retina, and a virtually
pathognomic 'dark choroid' pattern on fluorescein angiography. Stargardt
disease is classically inherited as an autosomal recessive trait, although
numerous families have been described in which features of Stargardt
disease are transmitted in an autosomal dominant manner. We have identified
a new kindred with autosomal dominant cone-rod dystrophy with
features of Stargardt-like disease. Detailed clinical evaluation, genotype
analysis, and linkage analysis were performed. Fluorescein angiography
revealed a 'dark choroid' pattern in three affected subjects. Electroretinography
disclosed markedly reduced scotopic and photopic responses in
three affected individuals. Genetic analysis revealed linkage to known
loci for cone-rod dystrophy (CORD7) and Stargardt-like disease
(STGD3) on chromosome 6q14. A peak lod score of 3.3 was obtained with the
marker D6S280 at straight theta =0.010. A physical map was
constructed by screening a YAC library with short tandem repeat markers
in the region. Screening of a candidate gene, the rho1 subunit of the
GABA receptor, failed to reveal any mutations.