GCH1 and systemic lupus erythematosus: Notably, one of the top GCH genes, Synaptotagmin XI (Syt11), plays an important role in regulating endocytosis and the vesicle-recycling process identified to be particularly significant in dopamine transmission, in addition to inhibiting cytokine secretion, such as interleukin-6 (IL6) and tumor necrosis factor (TNF), in macrophages and microglia [44]—both of these functions are potentially important in preventing the aberrant processes occurring in the lupus-prone brain.