Objective: To describe prevalence and demographics of Spinocerebellar Ataxia (SCA) 1,2,3,6 and 7, and the phenotypic characteristics of SCA 3 patients in Malaysia.

Background: Spinocerebellar ataxias are neurodegenerative diseases causing progressive degeneration of the cerebellum and brainstem, leading to ataxia, pyramidal and extrapyramidal syndromes. SCAs are highly heterogenous group of diseases with a wide genotype–phenotype spectrum. At present, there is no epidemiological data on SCA in Malaysia, mainly due to lack of genetic testing facilities locally. Since 2017, two centers in Malaysia have provided genetic testing facilities for the common SCA mutations (SCAs1,2,3,6,7) Here, we decsribe the prevalence of common SCAs in the Malaysian population and the clinical profile of these patients.

Method: We analysed data from all patients throughout Malaysia who underwent genetic testing in UKM Medical Center and Institute for Medical Research, from 2017 to 2020. Patients who were positive for SCA 1,2,3,6,7 were included in the decsription of clinical profile while patients with SCA 3 had detailed clinical phenotype evaluation including SARA scores.

Results: Of 156 patients who underwent genetic testing, 68 (68%) tested positive for either SCA 1,2,3,6,7. Of the 68 positive cases, 44 (68%) had SCA 3 followed by SCA 2 in 13(19%) and SCA 1 in 6 (8%). Detailed analysis of clinical phenotype was only available for 50 patients, with a mean age of 35.6 ±9.2 years and mean disease duration was 4.5 ± 2.9 years. Among the SCA 3 patients, cerebellar syndrome was present in 100%, pyramidal signs in 60%, parkinsonism in 13% and dystonia in 13%. The mean SARA at baseline (mean score, SD) was 12.3± 8.9.

Conclusion: The positive yield from SCA screening is 68%. SCA 3 is the commonest SCA in Malaysia, followed by SCA 2 and SCA 1. SCA 6 and SCA 7 were least common. The clinical characterictics of patients with SCA 3 is similar with that reported in other countries. There is a need to develop a proper registry of SCA patients to further understand the true prevalence and local impact of the disease.

References: 1. Sullivan, R., Yau, W.Y., O’Connor, E. et al. Spinocerebellar ataxia: an update. J Neurol 266, 533–544 (2019). https://doi.org/10.1007/s00415-018-9076-4 2. Paulson HL. The spinocerebellar ataxias. J Neuroophthalmol. 2009;29(3):227–237. doi:10.1097/WNO0b013e3181b416de 3. Ruano L, Melo C, Silva MC, Coutinho P (2014) The global epidemiology of hereditary ataxia and spastic paraplegia: a systematic review of prevalence studies. Neuroepidemiology 42(3):174–183

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MDS Abstracts - https://www.mdsabstracts.org/abstract/prevalence-and-clinical-profile-of-common-spinocerebellar-ataxia-in-malaysia/