Anti-IgLON5 disease | |
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Specialty | Immunology |
Anti-IgLON5 disease is an uncommon neurological autoimmune condition linked to autoantibodies directed against the IgLON5 protein. [1] Sleep disturbance, bulbar symptoms, and abnormal gait make up the majority of the clinical presentation, which is then followed by cognitive dysfunction. [2] The diagnosis of anti-IgLON5 disease is primarily based on clinical signs and the identification of IgLON5 antibodies in patient serum and/or cerebrospinal fluid. [1]
The IgLON proteins are a family of five cell-adhesion molecules IgLON 1, 2, 3, 4 & 5, which assist in neuronal growth and connections among nerve cells. [3] and help in brain evolution and maturation to maintain integrity of the blood brain barrier. [4]
Abnormal pTau deposits seen in several brains, brain stems and upper cervical cords shown by neuro-immuno-histochemistry studies of brain tissue from these regions without inflammatory cells differentiate this entity from other autoimmune encephalitis. [5] [6]
IgLON5 refers to a cell surface protein involved in promoting connections among nerve cells. [7] Prevalence of the HLA-DRB1*10:01 allele was greatly increased in people with anti-IgLON5 disease. [8] The sleep problems seen in this disorder are insomnia, sleep related abnormal movements called parasomnias which may be seen in both REM and NREM sleep and poor efficiency of sleep. Respiratory problems related to sleep disorder such as obstructive sleep apnea (OSA) and jerky stertorous breathing were noted in more than half the cases. [9]
Serum studies show IgLON5 antibodies in almost all patients while the presence of CSF antibodies is more sporadic, occurring in ~50% of cases. Additional findings may be Oligoclonal bands(OCB), a few leukocytes and a slight rise in proteins, with otherwise normal CSF examination in more than half the cases. [10]
If tau, p-tau or beta-amyloid are found then they indicate the neuropathology of the disorder, thereby distinguishing it from other autoimmune encephalitis.[ citation needed ]
MRI scans of the brain show brain stem atrophy in half the cases and changes in brain regions having tau-pathy in one fifths, FDG Positron emission scans-(FDG - PET)show hyper-metabolism in region of tau-pathy in half the cases correlating well with the clinical features.[ citation needed ]
Anti-IgLON5 disease is mainly treated with immunosuppressants (80%), mostly cycles of IV corticosteroids (58%) in combination with IV immunoglobulins (IVIg−36%) and/or TPE (27%). Alternative successfully used, second-line treatments are Rituximab (22%) and Cyclophosphamide (12%), Azathioprine and Mycophenolat Mofetil. [11] [12] [13]
Sudden death is the most common outcome in nearly 34% of patients, irrespective of partial response to therapy. While complications from aspiration were the other common cause of death. [14] [15] [16]
Symptomatic treatment with CPAP in patients with OSA helps improve respiratory symptoms, while parasomnias and movement disorders (myoclonus, parkinsonism, and dystonia) did not respond when antiepileptic, dopaminergic, and anti-hyperkinetic drugs were administered. [11] [16] [17]
Morvan's syndrome is a rare, life-threatening autoimmune disease named after the nineteenth century French physician Augustin Marie Morvan. "La chorée fibrillaire" was first coined by Morvan in 1890 when describing patients with multiple, irregular contractions of the long muscles, cramping, weakness, pruritus, hyperhidrosis, insomnia and delirium. It normally presents with a slow insidious onset over months to years. Approximately 90% of cases spontaneously go into remission, while the other 10% of cases lead to death.
Antinuclear antibodies are autoantibodies that bind to contents of the cell nucleus. In normal individuals, the immune system produces antibodies to foreign proteins (antigens) but not to human proteins (autoantigens). In some cases, antibodies to human antigens are produced.
Neuromyelitis optica spectrum disorders (NMOSD) are a spectrum of autoimmune diseases characterized by acute inflammation of the optic nerve and the spinal cord (myelitis). Episodes of ON and myelitis can be simultaneous or successive. A relapsing disease course is common, especially in untreated patients.
Stiff-person syndrome (SPS), also known as stiff-man syndrome, is a rare neurologic disorder of unclear cause characterized by progressive muscular rigidity and stiffness. The stiffness primarily affects the truncal muscles and is characterised by spasms, resulting in postural deformities. Chronic pain, impaired mobility, and lumbar hyperlordosis are common symptoms.
Experimental autoimmune encephalomyelitis, sometimes experimental allergic encephalomyelitis (EAE), is an animal model of brain inflammation. It is an inflammatory demyelinating disease of the central nervous system (CNS). It is mostly used with rodents and is widely studied as an animal model of the human CNS demyelinating diseases, including multiple sclerosis (MS) and acute disseminated encephalomyelitis (ADEM). EAE is also the prototype for T-cell-mediated autoimmune disease in general.
Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired autoimmune disease of the peripheral nervous system characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder is sometimes called chronic relapsing polyneuropathy (CRP) or chronic inflammatory demyelinating polyradiculoneuropathy. CIDP is closely related to Guillain–Barré syndrome and it is considered the chronic counterpart of that acute disease. Its symptoms are also similar to progressive inflammatory neuropathy. It is one of several types of neuropathy.
Paraneoplastic cerebellar degeneration (PCD) is a paraneoplastic syndrome associated with a broad variety of tumors including lung cancer, ovarian cancer, breast cancer, Hodgkin’s lymphoma and others. PCD is a rare condition that occurs in less than 1% of cancer patients.
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A paraneoplastic syndrome is a syndrome that is the consequence of a tumor in the body. It is specifically due to the production of chemical signaling molecules by tumor cells or by an immune response against the tumor. Unlike a mass effect, it is not due to the local presence of cancer cells.
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MOG antibody disease (MOGAD) or MOG antibody-associated encephalomyelitis (MOG-EM) is an inflammatory demyelinating disease of the central nervous system. Serum anti-myelin oligodendrocyte glycoprotein antibodies are present in up to half of patients with an acquired demyelinating syndrome and have been described in association with a range of phenotypic presentations, including acute disseminated encephalomyelitis, optic neuritis, transverse myelitis, and neuromyelitis optica.
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