Cases of familial PD have been shown to result from mutations in SNCA, encoding α-synuclein, and the G51D mutation (c.152 G > A) has been identified to cause an early onset and aggressive form of PD with associated dementia and multiple system atrophy (Kiely et al., 2013; Lesage et al., 2013). The gene discussed is SNCA; the disease is multiple system atrophy.