Antigliadin antibodies (AGAs) are antibodies of the IgA and IgG classes found in the serum of celiac disease patients. These antibodies mainly target gliadin-derived peptides, which are the main proteins of gluten. AGAs are not specific for celiac disease as they are also found in patients with other gastrointestinal diseases such as gastritis, gastroenteritis, and IBD.

Anti-gliadin IgG is an antibody that the immune system produces in response to gliadin, a component of gluten found in wheat, barley, and rye. When someone with a sensitivity to gluten consumes these grains, their immune system may mistakenly identify gliadin as a harmful substance and produce Anti-gliadin IgG to attack it. This reaction is often seen in individuals with celiac disease, an autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. However, Anti-gliadin IgG can also be present in non-celiac gluten sensitivity, where people experience symptoms similar to celiac disease but without the associated intestinal damage.

Glial fibrillary acidic protein (GFAP) is the major structural protein of the glial intermediate filament of astrocytes that forms part of the cytoskeleton of mature astrocytes and other glial cells, but is not found outside the CNS. Anti-GFAP is produced when the protein enters the bloodstream after a rupture of the blood brain barrier, thus serves as a blood based diagnostic marker of brain injury.

Glial fibrillary acidic protein (GFAP) is the major structural protein of the glial intermediate filament of astrocytes that forms part of the cytoskeleton of mature astrocytes and other glial cells, but is not found outside the CNS. Anti-GFAP is produced when the protein enters the bloodstream after a rupture of the blood brain barrier, thus serves as a blood based diagnostic marker of brain injury.

Glucose-regulating protein 78 (GRP78) is a molecular chaperone in the endoplasmic reticulum (ER) that promotes folding and assembly of proteins, controls the quality of proteins, and regulates ER stress signaling through Ca2+ binding to the ER. In tumors, GRP78 is often upregulated, acting as a central stress sensor that senses and adapts to changes in the tumor microenvironment, mediating ER stress of cancer cells under various stimulations of the microenvironment to trigger the folding protein response. 

Increasing evidence has shown that GRP78 is closely associated with the progression and poor prognosis of lung cancer, and plays an important role in the treatment of lung cancer.

Glucose-regulating protein 78 (GRP78) is a molecular chaperone in the endoplasmic reticulum (ER) that promotes folding and assembly of proteins, controls the quality of proteins, and regulates ER stress signaling through Ca2+ binding to the ER. In tumors, GRP78 is often upregulated, acting as a central stress sensor that senses and adapts to changes in the tumor microenvironment, mediating ER stress of cancer cells under various stimulations of the microenvironment to trigger the folding protein response. 

Increasing evidence has shown that GRP78 is closely associated with the progression and poor prognosis of lung cancer, and plays an important role in the treatment of lung cancer.

Anti-glycine receptor (GlyR) antibodies, including IgG and IgA classes, are autoantibodies directed against the glycine receptor, a key inhibitory neurotransmitter receptor in the central nervous system. The presence of these antibodies is most commonly associated with autoimmune disorders such as stiff-person syndrome (SPS) and its variants, including progressive encephalomyelitis with rigidity and myoclonus (PERM). These conditions are characterized by severe muscle stiffness, spasms, and functional impairment due to disrupted inhibitory signaling in the spinal cord and brainstem. The detection of anti-GlyR antibodies, especially of the IgG type, supports the diagnosis of these neurological disorders and can guide immunotherapy treatments. The IgA class of anti-GlyR antibodies may also have clinical relevance, although less is known about their exact role compared to IgG. The measurement of these antibodies is done through specialized laboratory tests, which can be critical for both diagnosis and management of affected individuals.

Anti-glycine receptor (Anti-GlyR) antibodies of the IgM class are a type of autoantibody directed against glycine receptors in the central nervous system. Glycine receptors are crucial for the regulation of motor and sensory pathways due to their inhibitory function in neurotransmission. When IgM antibodies bind to these receptors, they can disrupt normal inhibitory signaling, leading to a range of neurological symptoms.

The presence of anti-GlyR IgM is particularly significant because IgM is usually the first antibody class to rise in response to an antigen and can indicate an acute phase of an immune response. While less commonly discussed than IgG anti-GlyR antibodies, which are associated with conditions like stiff-person syndrome (SPS) and PERM (progressive encephalomyelitis with rigidity and myoclonus), IgM antibodies may also be implicated in similar disorders or suggest a different aspect of the immune response.

Detection of ganglioside M1 (GM1) antibodies, usually of the IgM isotype, is associated with multi-focal motor neuropathy and lower motor neuropathy, characterized by muscle weakness and atrophy. Multi-focal motor neuropathy may occur with or without high serum titers of anti-GM1 antibodies. GM1 antibodies are detected in approximately 50 % of persons with multi-focal motor neuropathy.

Detection of ganglioside M1 (GM1) antibodies, usually of the IgM isotype, is associated with multi-focal motor neuropathy and lower motor neuropathy, characterized by muscle weakness and atrophy. Multi-focal motor neuropathy may occur with or without high serum titers of anti-GM1 antibodies. GM1 antibodies are detected in approximately 50 % of persons with multi-focal motor neuropathy.

GM2 ganglioside is a potential peripheral nerve antigen for neuropathy-associated autoantibodies. Anti-GM2 IgM antibodies have been reported in some patients with dysimmune neuropathy or lower motor neuron syndrome, in whom they were often associated with a concomitant reactivity with GM1.

GM2 ganglioside is a potential peripheral nerve antigen for neuropathy-associated autoantibodies. Anti-GM2 IgM antibodies have been reported in some patients with dysimmune neuropathy or lower motor neuron syndrome, in whom they were often associated with a concomitant reactivity with GM1.

Histone antibodies are autoantibodies. These are antibodies produced by a person’s own immune system that target his or her own histones. Histones are proteins that are a part of chromatin, the genetic material present in the nucleus of almost all cells within the body. Because histones are found inside cells, this attack on “self” can cause symptoms throughout the body. This test detects the presence of histone antibodies in the blood.

Anti-HMGCR antibodies, also known as Anti-3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase antibodies, are a specific type of autoantibody targeting the HMGCR enzyme, a key component in the cholesterol synthesis pathway. These antibodies have gained significant attention in the field of rheumatology and autoimmunity, particularly in their association with statin-associated autoimmune myopathy, a condition characterized by progressive muscle weakness and elevated serum creatine kinase levels. Patients who develop this condition, often in the context of statin therapy, produce Anti-HMGCR antibodies that are believed to mediate an autoimmune response against muscle fibers.