Clinical characterisation and the improved molecular diagnosis of autosomal dominant conerod dystrophy in patients with SCA7


To evaluate the retinal phenotype and genetic features of Chinese patients with spinocerebellar ataxia
type 7 (SCA7).

Detailed ophthalmic examinations, including electroretinograms, fundus photography, fundus
autouorescence and optical coherence tomography, were performed to analyse the retinal lesions of
patients with SCA7. A molecular genetic analysis was completed to conrm the number of CAG repeats in
ATXN7 gene on the patients and their family members.

Eight patients from three families with SCA7 were included in this study. Trinucleotide repeat was
expanded from 43 to 113 in the affected patients. The affected patients were characterised by different
degrees of cone-rod dystrophy, which is positively related to the number of CAG repeats and age. All
patients complained of progressive bilateral visual loss, and most cases reported visual disturbance
earlier than gait movement or dysarthria. A coarse granular appearance of the macular region on
scanning laser ophthalmoscopy, hypouorescence in the macula on autouorescence, retinal atrophy on
optic coherence tomography, depression of multifocal electroretinograms and prominent abnormalities in
cone-mediated responses on electrograms are the general features of SCA7-related retinopathy.
Hyperreective dots in the outer retinal layers and choroidal vessel layers are a common sign in optic
coherence tomography in the advanced stage.

SCA shows a cone-rod dystrophy phenotype. The multimodal imaging of the retina is benecial to detect
the early lesions of cone-rod dystrophy related to SCA7.

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