Spinocerebellar ataxia in Singapore: predictive features of a positive DNA test?
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.
Tan
E K
EK
Department of Neurology, Singapore General Hospital, Singapore, Republic of Singapore.
Law
H Y
HY
Zhao
Y
Y
Lim
E
E
Chan
L L
LL
Chang
H M
HM
Ng
I
I
Wong
M C
MC
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*
D004247:DNA