α-Synuclein in blood and brain from familial Parkinson disease with SNCA locus triplication

The authors recently demonstrated that genetic triplication of the SNCA locus causes Parkinson disease. Here it is shown that SNCA triplication results in a doubling in the amount of alpha-synuclein protein in blood. Examination of brain tissue showed a doubling in the level of SNCA message. However, at the protein level in brain, there was a greater effect on deposition of aggregated forms into insoluble fractions than on net expression of soluble alpha-synuclein.