Modifications of S1P metabolism, S1PR expression profile, and S1P-mediated signaling have been described in neurodegenerative diseases, including multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease for recent reviews see [29,31,32] and neuropathic pain [33,34,35,36,37]. The gene discussed is MBTPS1; the disease is juvenile Huntington disease.