Additionally, we suspect the false negative rate is relatively high, and may undermine the actual rate of α-synuclein aggregation due to the following: sampling error due to the scattered distribution of α-synuclein positive protein in the gastrointestinal system, pathological tissue specimen processing may result in a loss of α-synuclein protein, the late stage degeneration of PD may obscure positive detection, or obvious submucosal layer staining may not be detected in some pathological tissues under an optical microscope. This evidence concerns the gene SNCA and Parkinson disease.