Dementia with Lewy bodies (DLB) is characterized by the widespread presence of 
Lewy bodies (LBs) in the brain. alpha-Synuclein, the main component of LBs, is 
expressed as two main isoforms (112 and 140), but little is known about their 
differential expression in the brain. We compared alpha-synuclein 112 and 
alpha-synuclein 140 expression levels in the prefrontal cortices of six DLB 
patients, eight Alzheimer disease (AD) patients, and six control subjects. 
Relative alpha-synuclein 112 and alpha-synuclein 140 expression levels were 
determined by real-time polymerase chain reaction with competimer technology 
using a LightCycler System. Whereas total alpha-synuclein levels were just 
marginally elevated in DLB in comparison with the other groups, alpha-synuclein 
112 was seen to be markedly increased in DLB compared with AD cases and 
controls. In contrast, alpha-synuclein 140 levels were significantly diminished 
in both neurodegenerative disorders in comparison with controls. These results 
show differential overexpression of alpha-synuclein 112 in DLB, a finding that 
could be of importance in DLB pathogenesis.