[Relationship between alpha-synuclein and Parkinson's disease]

Alpha-synuclein(SNCA) is a major component of Lewy bodies. Lewy bodies were appeared in some neurodegenerative disorders known as Alzheimer's disease or Parkinson's disease. Recently SNCA multiplications were reported in several autosomal familial Parkinson's disease (ADPD). In two triplication pedigree, the double expression level of alpha-synuclein was reported in both peripheral blood and brain. And the some affected patients in SNCA multiplication family also had more severe prognosis than sporadic patients. They were suffered from cognitive decline and severe parkinsonism. Mainly triplication patients were showed severe prognosis compared to duplication patients. They had young onset and non-responsiveness to levodopa. On the other hand, duplication patients had milder course similar with sporadic cases. These analysis were suggested that the gain of function mechanism on SNCA could cause severe dementia like diffuse Lewy bodies and high amount of Lewy bodies in brain. And the differences of length between triplication and duplication also might be influenced on clinical aspects. In this review, we described about the clinical and genetic aspects of alpha-synuclein, not only SNCA multiplication but also mis-sense mutation of SNCA.