Objective: ​​​​​We described the clinical features and phenotypic presentation of 40 patients who was diagnosed with spinocerebellar ataxia type 8 (SCA8) in a single tertiary referral center in Taiwan.

Background: Spinocerebellar ataxia type 8 is an autosomal dominant, progressive neurodegenerative disease. The onset age is between 1 to 73 in previous reports. The disease is confirmed via genetic testing for CTA/CTG expansion on chromosome 13q21. Patients may exhibit a wide range of neurological manifestations, including cerebellar signs, pyramidal signs, cognitive impairment, autonomic dysfunctions, or peripheral neuropathy and therefore, often poses diagnostic difficulties.

Method:
 ​​​Taipei Veterans General Hospital is a tertiary referral center in Taiwan. We collected the information of patients diagnosed with spinocerebellar ataxia type 8 from 2014 to 2018. Demographic data, clinical features and genetic information were gathered via electrical medical records from all the patients. The results were analyzed with R (R Core Team, 2019).

Results:
 ​​​​​A total of 40 patients’ medical records were collected, including 18 male and 22 female patients. The average age of onset was 45.5 ± 19.1 year-old, and there was no significant difference between genders. (male: 45.9 year-old, female 45.2 year-old, p = 0.92). The average CTA repeats was 130.4 (Range: 87-229). Cerebellar signs were seen in 65% patients. Other than cerebellar signs, 55% patients had parkinsonism features, 50% patients complained of dysphagia or dysarthria, 35% patients had peripheral neuropathy, and 10% presented features of lower motor neuron signs with or without upper motor neuron signs, which were suspicious for motor neuron diseases. Tremor was presented in 7 out of 40 patients, and among them, 3 demonstrated a no-no type head tremor. Cognitive function impairments were observed in 8 out of 40 patients, and 4 patients presented memory decline.

Conclusion:
  ​​​​​Spinocerebellar ataxia type 8 has a wide range of phenotypical presentations. Patients with an autosomal dominant family history, who has a mixed neurological presentation of ataxia, parkinsonism, upper and lower motor neuron signs, peripheral neuropathy and/or no-no type tremor should be tested for CTA/CTG trinucleotide expansion on chromosome 13q21.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-phenotypical-presentation-of-sca8-in-taiwan/