Anti-IgLON5 disease is a

neurodegenerative A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic ...

autoimmune disease An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...

. It is marked by

parasomnia Parasomnias are a category of sleep disorders that involve abnormal movements, behaviors, emotions, perceptions, and dreams that occur while falling asleep, sleeping, between sleep stages, or during arousal from sleep. Parasomnias are dissociate ...

s and

chorea Chorea (or choreia, occasionally) is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term ''chorea'' is derived from the grc, χορεία ("dance"; see choreia), as the quick movement ...

- an involuntary movement disorder. __TOC__

Pathophysiology

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. and help in brain evolution and maturation to maintain integrity of the

blood brain barrier Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the Cell (biology), cells, and transports Metabolic waste, metabolic waste products away from th ...

. 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. IgLON5 refers to a cell surface protein involved in promoting connections among nerve cells. Prevalence of the

HLA-DRB1 HLA class II histocompatibility antigen, DRB1 beta chain is a protein that in humans is encoded by the ''HLA-DRB1'' gene. DRB1 encodes the most prevalent beta subunit of HLA-DR. DRB1 alleles, especially those encoding amino acid sequence changes at ...

*10:01

allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

was greatly increased in people with anti-IgLON5 disease. 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.

Diagnosis

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. If tau, p-tau or beta-amyloid are found then they indicate the neuropathology of the disorder, thereby distinguishing it from other autoimmune encephalitis.

Brain Imaging

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.

Treatment

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 Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in non-geriatric p ...

(22%) and

Cyclophosphamide Cyclophosphamide (CP), also known as cytophosphane among other names, is a medication used as chemotherapy and to suppress the immune system. As chemotherapy it is used to treat lymphoma, multiple myeloma, leukemia, ovarian cancer, breast cancer ...

(12%),

Azathioprine Azathioprine (AZA), sold under the brand name Imuran, among others, is an immunosuppressive medication. It is used in rheumatoid arthritis, granulomatosis with polyangiitis, Crohn's disease, ulcerative colitis, and systemic lupus erythematosus, ...

and Mycophenolat Mofetil. 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. 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.

References

{{reflist Autoimmune diseases Encephalitis