Late-Onset Tay-Sachs Disease With SMALED-Like Muscle MRI Pattern Despite a Distinct Clinical Phenotype.
Rodrigo Siqueira Soares Frezatti, Trajano Aguiar Pires Gonçalves, Manoella Guerra de Albuquerque Bueno et al.
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Case in brief
Two female patients in their second decade presented with slowly progressive, lower limb-predominant flaccid weakness and tremor. Electromyography indicated a neurogenic pattern, and whole-body muscle MRI revealed selective fatty infiltration resembling that seen in spinal muscular atrophy with lower extremity predominance (SMALED). Genetic testing confirmed compound heterozygous variants in the HEXA gene, consistent with late-onset Tay-Sachs disease.
What made this case unusual
The muscle MRI findings in late-onset Tay-Sachs disease showed a pattern similar to SMALED, which is not typically associated with this condition, highlighting the potential for diagnostic confusion.
Diagnostic / clinical pearl
Clinicians should be aware that late-onset Tay-Sachs disease can present with muscle MRI findings that overlap with those of spinal muscular atrophy, necessitating careful interpretation to avoid misdiagnosis.
Why it matters
Understanding the imaging characteristics of late-onset Tay-Sachs disease can improve diagnostic accuracy and ensure appropriate genetic testing is performed.