We further investigated age-dependent changes in the alpha-synuclein proteoforms present in the appendix and SN and found that synucleinopathy appendix had a significant gain in full-length synuclein (alpha-synucleinac1−140) with age, which was not observed in the appendix of unaffected controls (q<0.05, linear regression; Supplementary Figure S2). Here, SNCA is linked to synucleinopathy.