The level of tyrosine in α-Syn transgenic mice is reduced, which may be due to PD making phenylalanine too high, inhibiting tyrosine hydroxylase activity, reducing tyrosine content, and hindering normal neurotransmitters (dopamine and normethyl), adrenaline synthesis, so the abnormal tyrosine metabolism will cause the disorder of phenylalanine metabolism and energy metabolism, which will affect the overall condition of the body. Here, TH is linked to Parkinson disease.