This seems a little controversial, but if we take a closer look at these results against the involvement of DNA methylation in PD, we can find that these examinations taken with blood cell samples are much less convincing than those taken with brain cell samples in that α-synuclein is widely believed to mainly be localized and functional in mammalian brain neurons (Mclean et al., 2000; Yu et al., 2007). The gene discussed is SNCA; the disease is Parkinson disease.