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. This evidence concerns the gene XDH and Huntington disease.