Genetic analysis of SCA 2 and 3 repeat expansions in essential tremor and atypical Parkinsonism.
Anecdotal reports suggest that patients with spinocerebellar ataxia (SCA 2) patients can present with postural tremor with ataxia. We determined the prevalence of SCA2 and SCA3 mutations in a cohort of ET and atypical Parkinsonism patients. A total of 277 subjects comprising of 177 ET and 100 atypical Parkinsonism were examined. We identified one positive case of SCA3 among those who were diagnosed with ET, yielding a prevalence of 0.5%, but a zero prevalence among our atypical Parkinsonism patients. No study subjects carried an abnormal SCA2 repeat expansion. Our study highlights that SCA3 can present initially with ET symptoms, expanding the spectrum of genetic diseases that can be associated with ET-like phenotype. Routine screening for SCA2 and SCA3 in ET and atypical Parkinsonism patients may not be cost effective. However, in the long-term follow-up of patients who present with an ET phenotype, clinicians should be vigilant for other neurological signs, which may be point to an alternate diagnosis.
Tan
Eng-King
EK
Department of Neurology, Singapore General Hospital, Singapore. gnrtek@sgh.com.sg
Tong
Justina
J
Pavanni
Ratnagopal
R
Wong
Meng-Cheong
MC
Zhao
Yi
Y
D000328:Adult; D000978:Antiparkinson Agents / Q000627:therapeutic use; D000067699:Ataxin-3; D000067528:Ataxins; D003430:Cross-Sectional Studies; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D004351:Drug Resistance; D020329:Essential Tremor / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D019957:Motor Skills Disorders / Q000175:diagnosis / Q000235:genetics; D019578:Multiple System Atrophy / Q000175:diagnosis / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009460:Neurologic Examination; D009687:Nuclear Proteins / Q000235:genetics*; D020734:Parkinsonian Disorders / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012097:Repressor Proteins / Q000235:genetics*; D020754:Spinocerebellar Ataxias / Q000175:diagnosis / Q000235:genetics; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis / Q000235:genetics; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*; D018911:Trinucleotide Repeats
D000978:Antiparkinson Agents; D000067528:Ataxins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D007980:Levodopa; C092341:ATXN3 protein, human; D000067699:Ataxin-3