The outcomes of this research indicated that the lymphocyte count in peripheral blood was significantly lower in the PD patients compared with in the control group, which might be relevant towards the lymphocytes being recruited to the brain parenchyma due to blood-brain barrier dysfunction, leading to an imbalance in lymphocytes and reductions in the CD3+ as well as CD4+ lymphocyte subsets within patients with PD; this reduction is especially prominent in the subpopulation of CD3+ lymphocytes, which is typically the most abundant [7, 30]. The gene discussed is CD4; the disease is Parkinson disease.