Some embodiments herein related to methods, composition, and/or uses for reducing the likelihood of, delaying the onset of, or ameliorating one or more symptoms associated with Rett syndrome or Huntington's disease. Without being limited by theory, it is contemplated that modulation of gut microbiota can affect symptoms of Rett syndrome and Huntington's disease. Compositions or product combinations comprising, consisting essentially of, or consisting of bacteria and/or antibiotics can be administered to subject in need thereof so as to reduce the likelihood of, delay the onset of, or ameliorate the symptoms.
