title: Spinocerebellar ataxia in Singapore: predictive features of a positive DNA test?
abstract: Significant differences in frequency of the different spinocerebellar ataxia (SCA) subtypes have been described to occur in different populations. A 'blunderbuss' diagnostic DNA testing approach would entail unnecessary healthcare cost. In this study, we determine the prevalence of SCA subtypes and predictive features of a positive DNA test in consecutive clinically diagnosed SCA cases in Singapore. Twenty-one consecutive patients from 14 families were evaluated over a 3-year period. Thirteen patients (61.9%) from 6 families had a positive DNA test. Eleven of these (all ethnic Chinese) had SCA 3 (abnormal CAG size ranged from 61 to 71), and 2 ethnic Malays had SCA 2 (abnormal CAG size of 39). Clinical features which were highly predictive of a positive DNA SCA test in our population included presence of a positive family history, chorea and dystonia, muscle and tongue fasciculations, gaze-evoked nystagmus, and hypertonia. Our study draws attention to the observation that knowledge of relatively specific features of the most common SCA subtype in a local population can greatly enhance the practical accuracy of the choice of which SCA DNA test to order.
authors.affiliation: Department of Neurology, Singapore General Hospital, Singapore, Republic of Singapore.
authors.forename: E K
authors.initials: EK
authors.lastname: Tan
authors.forename: H Y
authors.initials: HY
authors.lastname: Law
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: E
authors.initials: E
authors.lastname: Lim
authors.forename: L L
authors.initials: LL
authors.lastname: Chan
authors.forename: H M
authors.initials: HM
authors.lastname: Chang
authors.forename: I
authors.initials: I
authors.lastname: Ng
authors.forename: M C
authors.initials: MC
authors.lastname: Wong
mesh_terms: D000328:Adult; D004247:DNA / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D005828:Genetics, Population; D006801:Humans; D008297:Male; D008875:Middle Aged; D012846:Singapore; D013132:Spinocerebellar Degenerations / Q000145:classification / Q000175:diagnosis / Q000235:genetics*
chemical_list: D004247:DNA