TH and Parkinson disease: Richfield et al. 20 introduced a mouse model expressing double mutated human aSyn gene with both A30P and A53T point mutations under the rat tyrosine hydroxylase (TH) promoter (C57BL/6J-Tg(TH-SNCA*A30P*A53T)39Eric/J) that combined two well-characterized familial site mutations of SNCA to model PD.