Abstract: The invention features methods, systems, and compositions for diagnosing non-central nervous system (non-CNS) disorders by detecting changes in gene expression in the CNS, e.g., in cerebrospinal fluid, in brain or spinal cord tissue samples, or other bodily fluid samples.

Abstract: Methods for treating a neurodegenerative disease in a mammal, specifically methods for treating Parkinson's disease. The treatment is based on administering an effective amount of a TNF-related molecules and/or TNF down regulating molecules, acting preferably in the substantia nigra. The effects of TNF over the substantia nigra are disclosed. Low concentration of TNF provides a neuroprotective activity and high concentration of TNF provides a neurodegenerative effect on the mammal. The method is based on a treatment with TNF wherein the concentration of TNF in the patients affected by the Parkinson's disease is regulated. In addition, a treatment in which molecules activate a survival signal into neurons via TNFR 2 receptors is provided. A new animal model for Parkinson's disease studies is also provided, wherein the adenovirus vector, the CRE/loxP and transgenic knock-in mice are combined.