A study using immunohistochemical imaging of punch skin biopsies from Parkinson's patients showed that alpha-synuclein was increased and protein gene product 9,5 (PGP 9,5) was reduced in autonomic adrenergic and cholinergic C-fibers, indicating an overall loss of nerve fibers and deposition of alpha-synuclein in the remaining fibers. This evidence concerns the gene SNCA and Parkinson disease.