SNCA and Parkinson disease: Mutations and multiplications in SNCA, the gene encoding αsyn, have been identified in some cases of familial PD and these have occasionally been found to have oligodendroglial inclusions resembling GCIs (Gwinn-Hardy et al. 2000; Kiely et al. 2013; Markopoulou et al. 2008; Obi et al. 2008).