Anti-MAG peripheral neuropathy (Immunoglobulin M(IgM) Anti-Myelin Associated Glycoprotein Peripheral Neuropathy) is a rare autoimmune variety of peripheral neuropathy. In this type of PN, a person’s own immune system attacks cells that are specific in maintaining a healthy peripheral nervous system. As these cells are destroyed by antibodies, they lose function and create problems in both sensory and motor function.
Anti-MAG neuropathy is often associated with “monoclonal gammopathy of undetermined significance (MGUS),” a potentially cancerous (but usually benign) condition characterized by a similar over production of serum immunoglobulins.
Symptoms & Signs
(Not all symptoms and signs may be present.)
The disorder is predominantly characterized by the following symptoms:
- Sensory loss starting in toes and/or fingers
- Loss of vibration senses
- Unsteady gait
- Tremors in hands and legs
- Poor balance
- Muscle weakness
Diagnosis proceeds with a neurological examination. If the examination indicates that the patient has a peripheral neuropathy, then testing for a monoclonal gammopathy and electrodiagnostic testing is done among many other tests. If the blood work and/or the EMG are appropriately abnormal, then blood testing for anti-MAG antibody is done. Other blood work may be done to exclude another cause for the patient’s condition. Some patients will have an elevated protein in their cerebral-spinal fluid, which can be obtained through a spinal tap.
Treatment & Therapy
(Not all treatments and therapies may be indicated.)
The progression of anti-MAG may be slower and less severe than CIDP (Chronic Inflammatory Demyelinating Polyneuropathy), and many patients continue living relatively normal lives while managing their symptoms with simple exercises or drug therapies. Only 10 percent of patients become severely disabled and wheelchair-bound. The majority of patients are male, and most of them are in their 50s or 60s.
There are many therapeutic treatments that have been tried for anti-MAG neuropathy, with varying results.
- Rituximab – an antibody that binds to B- cells (cells that make antibodies) and removes them from the blood, cutting off the production of anti-MAG antibodies at the source. While helpful to some patients, studies have been inconclusive.
- Cyclophosphamide – a drug that is often used in the treatment of lymphomas, works by rapidly killing dividing cells, such as antibody-producing B-Cells, which in turn decreases antibody levels. This may improve quality of life and sensory loss; however, a long-term risk of cancer with chronic use of this treatment is possible.
- IVIg (Intravenous Immunoglobulin) – infusions help small segments of patients in the initial phase of the disease, though is not necessary effective in treating anti-MAG neuropathies.
- Steroids and plasma exchange treatments are not recommended for anti-MAG.
- Current immune therapies – while temporarily effective in some patients – are mostly reserved for patients impaired in their daily activities, or for patients in a progressive phase of the disease.
Current research is limited and has focused mostly on determining treatment options. This has been studied through clinical trials with drugs listed previously or through new therapy techniques that delay loss in function. Most drugs being studied are immunosuppressants that can attack the antibodies or other aspects in the hope of preventing damage to the Schwann cells. This will, ideally, prevent the loss of myelination on peripheral nerve fibers.
A global collaborative study called the IMAGiNe Research Study aims to gather more knowledge about anti-MAG by creating an international database of patient information for research and study. The program began in the Netherlands in 2016, expanded to the UK, Spain, Serbia, Italy, France, Switzerland and the US in 2017. The Foundation for Peripheral Neuropathy is providing funding for the continued expansion of the program in the United States. More information on the IMAGiNe study can be found here.
Please click here to watch FPN’s webinar on Anti-MAG PN, featuring Richard Lewis, MD. Webinar held live June 27, 2022.
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