Machado-Joseph disease (MJD), or spinocerebellar ataxia type 3, is characterized by remarkable clinical heterogeneity. We present a MJD family in which variable phenotypes were noted in affected members, including one presenting predominantly with spastic paraparesis. A review of the literature revealed that MJD with the initial presentation of spastic paraparesis is more frequently observed in cases of eastern Asian origin who carry a greater CAG expansions in the ATXN3 gene. A greatly expanded allele in ATXN3 combined with an eastern Asian genetic background is associated with a phenotype of spastic paraparesis in MJD.
Keywords: Machado-Joseph disease; Phenotype; Spastic paraparesis; Spinocerebellar ataxia type 3; Trinucleotide repeat.
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