SNCA and Parkinson disease: A study of a single case of G2019S LRRK2 PD without LB revealed the presence of small soluble α-synuclein oligomers in the cortex (Gomez and Ferrer, 2010), while another study has shown very low levels of insoluble α-synuclein in 4 G2019S LRRK2 PD cases with LB compared to sporadic PD cases (Mamais et al., 2013).