Astrocyte dysfunction, as a result of HIV infection, is associated with compromised blood–brain barrier integrity, neuronal survival as well affecting synapses through a Tat-mediated release of extracellular vesicle microRNA-7 leading to reduced synaptic densities by downregulating neuroligin-2 in neurons (Hu et al. 2020; Ton and Xiong 2013). The gene discussed is TAT; the disease is HIV infectious disease.