Furthermore, investigations into the pathogenic role of microglia have documented chronic overexpression of TGF-β1 in multiple neurodegenerative diseases, including Alzheimer’s disease, frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS), and Parkinson’s disease (PD) (Martinez-Canabal et al., 2013, Wirths et al., 2010), illustrating that this pathway may be contributing to numerous age-related diseases in which the synapse is an early pathological target. This evidence concerns the gene TGFB1 and Parkinson disease.