In addition, decreased mRNA levels in CD4 + T cells of signal transducer and activator of transcription 1 (STAT1), driving Th1 differentiation, and nuclear receptor subfamily 4 group A member 2 (NR4A2)/STAT6 involved in the Treg development were detected in patients with PD having motor complications compared to those without motor complications, which gives a new opinion of the therapeutic management of PD (Kustrimovic et al., 2018; Contaldi et al., 2020). Here, CD4 is linked to Parkinson disease.