TGM2 and Parkinson disease: Notably, in vivo studies in genetically modified mice that are transgenic for α-Syn and either over-express TG2 (TG2Tg/SynTg) or have deletion of the TG2 gene (TG2−/−/SynTg) support the contribution of TG2 to the pathogenesis of PD by crosslinking α-Syn [30,145,146].