Spinocerebellar Ataxia Type 12: Spectrums of Movement Disorders and Clinical Features.

BACKGROUND

Spinocerebellar ataxia type 12 (SCA12) is a neurodegenerative disorder caused by a CAG repeat expansion in the PPP2R2B gene. It is characterized by tremor, cerebellar ataxia, and a wide range of neurological symptoms. The heterogeneity of SCA12 symptoms, particularly in movement presentation, highlights the need for standardized studies to better define its clinical spectrum.

SUMMARY: This review evaluates the spectrum of movement disorder symptoms, focusing on their type, age of onset, and progression, and highlights areas requiring further research. Tremor, typically action or postural, is often the initial symptom, followed by progressive cerebellar dysfunction, including gait instability, dysmetria, and dysdiadochokinesia, supported by neuroimaging evidence of cerebellar atrophy. Other movement-related features, such as dystonia and parkinsonism, further complicate the clinical picture. Psychiatric manifestations, including cognitive decline and depression, are also reported, though their prevalence varies. A clear characterization of the movement symptoms of SCA12 will guide future research into targeted therapeutic strategies, addressing the significant unmet needs of affected patients. This review underscores the importance of a multidisciplinary approach to studying SCA12, combining all relevant clinical data to advance knowledge and improve patient outcomes.

KEY MESSAGES: SCA12 presents predominantly with tremor, often preceding cerebellar signs by years. The clinical phenotype is broader than previously recognized, including dystonia, parkinsonism, and neuropsychiatric symptoms. Clinical variability may delay suspicion of SCA12, supporting early genetic testing. Systematic clinical characterization is critical for improving patient management.