Severing the vagus nerve, rather than removing the appendix, can also hinder the propagation of alpha-synuclein from the gut to the brain in mice (Kim et al., 2019) and humans (Svensson et al., 2015) and improve a Parkinson’s-like affliction and Parkinson’s itself in, respectively, animals and humans (Borghammer, 2018; Liddle, 2018; Lionnet et al., 2018; Fitzgerald et al., 2019; Kim et al., 2019; Munoz-Pinto et al., 2021). Here, SNCA is linked to Parkinson disease.