Trinucleotide Repeats Number in SCA2, SCA3, and SCA17 in Early-Onset Parkinson's Disease

BACKGROUND: Abnormal expansion of trinucleotide repeats in genes causing spinocerebellar ataxias such as SCA2, SCA3, SCA8, or SCA17 was reported in sporadic or familial Parkinson's disease. Genetic factors play an important role especially in early-onset Parkinson's disease (EOPD). To investigate mutations of ATXN2, ATXN3, and TBP as a possible cause in Korean EOPD, we analyzed mutations in these genes. We also investgated the possibility that trinucleotide repeats numbers in these genes contribute to the development of EOPD. METHODS: Mutation analysis of ATXN2, ATXN3, and TBP was done in 153 EOPD defined as age-at-onset before 51. Distribution of CAG repeats numbers were compared between EOPD and age- and sex-matched controls. RESULTS: No patients with EOPD had CAG repeats numbers in ATXN2, ATXN3, and TBP in mutation range. There was no difference in the distribution of CAG repeats between EOPD and controls, although we found a trend that CAG repeats numbers in ATXN3 appear larger in EOPD than in controls. CONCLUSIONS: Mutations of genes causing SCA2, SCA3, or SCA17 may not be a common genetic cause in Korean EOPD.

Use of the Putamen/Caudate Volume Ratio for Early Differentiation between Parkinsonian Variant of Multiple System Atrophy and Parkinson Disease

BACKGROUND AND PURPOSE: Neuropathological studies have demonstrated that multiple system atrophy (MSA) produces selective atrophy of the putamen with sparing of the caudate nucleus, while both structures are spared in idiopathic Parkinson's disease (PD). In this study we evaluated the clinical efficacy of using putaminal atrophy in brain MRI to differentiate MSA and PD. METHODS: We measured the putamen/caudate volume ratio on brain MRI in 24 patients with MSA and 21 patients with PD. Two clinicians who were blinded to the patients' diagnoses and to each other's assessments measured the volume ratio using a computer program. RESULTS: The measured volume ratios of the two investigators were highly correlated (r=0.72, p<0.0001). The volume ratio was significantly lower in MSA (1.29+/-0.28) than PD (1.91+/-0.29, p<0.0001). Setting an arbitrary cutoff ratio of 1.6 resulted in about 90% of patients with MSA falling into the group with a lower ratio, whereas more than 80% of patients with PD belonged to the other group. CONCLUSIONS: The present results demonstrate that putaminal atrophy in MSA as measured on brain MRI represents an effective tool for differentiating MSA from PD.