Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): Year of the Zebra 2026

Myelin oligodendrocyte glycoprotein antibody-associated disease, or simply MOGAD, is a rare autoimmune condition that affects the brain, spinal cord, and optic nerves. It happens when the immune system mistakenly targets a protein that sits on the surface of myelin, the protective coating that wraps around nerve fibers and helps nerve signals travel more quickly and efficiently.

Because this protein exists only in myelin-producing cells in the central nervous system, the immune system attack only targets the myelin in these areas, which explains why nerves elsewhere in the body are not affected. The exact reason why the attack develops in the first place is largely unknown, although it appears that viral illnesses might act to trigger an autoimmune response in some individuals, particularly children.

Symptoms of MOGAD depend on which part of the nervous system is affected, and they usually develop over several days. These episodes are often called attacks or relapses, and they can be one-time events or recur over time.

One of the most common manifestations is optic neuritis, which means inflammation of the nerve that connects the eye to the brain. This can cause eye pain that worsens with movement, blurred vision, partial or complete vision loss, and colors that appear washed out. Unlike other demyelinating diseases, MOGAD tends to affect both eyes simultaneously.

Another common presentation is inflammation of the spinal cord, known as myelitis. This can cause weakness in the arms or legs, numbness or tingling, difficulty walking, or problems with bladder and bowel control.

MOGAD can also cause inflammation in the brain, causing encephalitis. In children, brain inflammation typically appears as acute disseminated encephalomyelitis, or ADEM, which affects large areas of the brain at once. This can lead to symptoms that come on suddenly and are quite widespread, such as headaches, confusion, extreme fatigue, seizures, changes in consciousness, or changes in behavior.
Adults with MOGAD can also experience encephalitis, but afflicted brain areas are usually more localized, though symptoms such as headaches, confusion, or seizures are still seen.