The nervous system is an intricate, highly developed system that regulates and synchronizes the body's activities. The nervous system is an organ system which contains a grid of specialized neuronal cells called neurons. The human nervous system consists of two major parts called the central nervous system and the peripheral nervous system. The central nervous system in vertebrates contains the brain, spinal cord, and eyes. The peripheral nervous system contains sensory neurons which connect peripheral body parts to each other and to the central nervous system. Neurons, whether in the peripheral or central nervous system, function by transmitting chemical and/or electrical signals between each other, typically across a space called a synapse. Chemical messengers involved in the signal transmission between neurons are called neurotransmitters. These neurotransmitters are stored within synaptic vesicles in the membrane of the axon terminal. The chemicals can be released into the synaptic cleft and bind to receptors on the opposide side of the synapse. This action creates an action potential and propagates a particular signal using graded electrical potentials. There are many different classes of neurotransmitters implicated in many different biological and neurological processes. Classes of neurotransmitters include amino acids, monoamines and biogenic amines, peptides, and other types. Examples are glutamate, dopamine, epinephrine, opioid peptides, acetylcholine, nitric oxide, and adenosine.

Anti-GTP cyclohydrolase 1 antibody binds against the target GTP cyclohydrolase 1 (GCH1). GTP cyclohydrolase is an enzyme localized in the cytoplasm and in the nucleus. CGH1 is localized in the epidermis. GTP cyclohydrolase 1 positively regulates nitric oxide synthesis in umbilical vein endothelial cells and may be involved in dopamine synthesis. Defects in GCH1 are the cause of GTP cyclohydrolase 1 deficiency and dystonia type 5. GTP cyclohydrolase 1 deficiency (otherwise known as Segawa Syndrome) is a genetic disorder that can cause physical rigidity and developmental delay. Dystonia type 5, or dopamine responsive dystonia, is a neurological movement disorder characterized by sustained muscle contractions that cause twisting and repetitive movements or abnormal postures. Treatment for dystonia type 5 is the use of L-dopa. Anti-GAD antibody binds against the target glutamate decarboxylase 1. GAD catalyzes the production of GABA. Defects in GAD1 are the cause of cerebral palsy spastic quadriplegic type 1. Quadriplegia is a form of cerebral palsy in which both legs and both arms are affected. Quadriplegia Cerebral Palsy is characterized by severe motor dysfunctions in which affected individuals suffer a loss of both motor and sensory functions.