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K. Ochiai, S. Shimizu, Y. Saito, K. Matsumura, Y. Ichikawa, H. Tsukamoto, T. Shimizu, Y. Suzuki; Pigmentary Macular Dystrophy in Spinocerebellar Ataxia Type 1 . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5806.
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Autosomal dominant spinocerebellar ataxias (SCAs) are slowly progressive disorder often accompanied by ocular abnormalities such as nystagmus, ophthalmoparesis, retinal degeneration, and optic atrophy. These diseases are caused by expansion of a CAG trinucleotide repeat within the responsible genes. Among SCAs, SCA1 and SCA7 are known to develop visual impairment due to optic atrophy and pigmentary macular dystrophy, respectively. Thus far, there has been no case reports of SCA1 complicated by pigmentary macular dystrophy. Here we report a SCA1 case diagnosed by genetic analysis who developed pigmentaray macular dystrophy.
The patient is a 56–year–old Japanese man. His younger sister who has been diagnosed as spinocerebellar degeneration (SCD) elsewhere also suffers from recent and progressive deterioration of vision. A complete ophthalmologic examination was performed including best–corrected visual acuity, slit–lamp biomicroscopy, funduscopy, Goldmann perimetry, and electroretinography. From the patients genomic DNA, amplification of the CAG repeat–containing fragment in the SCA1 gene and SCA7 gene was performed by means of polymerase chain reaction (PCR) and the size of the PCR products were analyzed.
The patient was diagnosed as SCD at the age of 45 years. The patient began to complain of visual impairment at the age of 51 years. Ophthalmologic examination at the age of 56 years revealed that his best–corrected visual acuity was 0.2 OD and 0.1 OS. Fundus examination showed macular degeneration in both eyes. The foveal reflex was lost and coarse granular appearance with very small clumps of pigment in macular area was noted. No abnormalities were observed outside the macular region. A relative central scotoma in both eyes was detected by Goldmann perimetry. The single–flash electroretinography showed negative b–wave pattern and mild attenuation of the oscillatory potentials. The photopic electroretinography also showed mild attenuation of the each waves. The patient had a normal allele with 25 CAG repeats and an expanded allele with 48 CAG repeats in SCA1 gene, whereas he had homo normal alleles with 14 CAG repeats in SCA7 gene.
Clinically, the presence of pigmentary macular dystrophy has been an important factor to classify SCAs. However, this case shows that pigmentary macular dystrophy can be accompanied by SCA1 as well as SCA7.
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