The bibliography was searched in the PubMed and Google Scholar databases using the keywords “Alzheimer’s disease”, “amyotrophic lateral sclerosis”, “Huntington’s disease”, “multiple sclerosis”, “neurological disorders”, “oxidative stress”, “Parkinson’s disease”, “stroke”, “uric acid”, and “xanthine oxidoreductase” in appropriate combinations. The gene discussed is XDH; the disease is nervous system disorder.