Pro-inflammatory cytokines, such as interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α), are increased in PD compared to controls [81], and the levels of these cytokines are associated with the severity of motor and non-motor symptoms; to this end, pro-inflammatory cytokines have been suggested as a marker for early PD to predict disease prognosis [82]. Here, IL1B is linked to Parkinson disease.