SNCA and Parkinson disease: Histopathological hallmarks of PD include presence of Lewy bodies and Lewy neurites that are primarily composed of aggregated α‐synuclein (α‐syn).4 Furthermore, genetic studies point to a causal role of α‐syn in PD, as mutations and duplications of the gene coding for α‐syn, SNCA, have been linked to inherited forms of PD.