LIF and Parkinson disease: In terms of the CSF:serum ratios of the analytes, the LRRK2+/PD group had significantly decreased concentration ratios of TNF-RII (p = 0.008), SDF-1 alpha (p = 0.013), IL-16 (p = 0.042) and LIF (p = 0.049) compared to LRRK2-/PD.