Alexander Disease: A Rare Neurological Disorder
Alexander disease is a rare genetic disorder that affects the nervous system. It is a type of leukodystrophy, which means it damages the white matter of the brain. White matter is made up of nerve fibers covered in a fatty substance called myelin, which helps transmit nerve impulses. In Alexander disease, the myelin breaks down, and abnormal protein clumps called Rosenthal fibers accumulate in the brain. This disrupts the normal functioning of the nervous system.
There are different types of Alexander disease, classified by when symptoms first appear:
- Neonatal (early-onset): Symptoms begin soon after birth and are severe, including seizures, fluid buildup in the brain, and significant motor and intellectual impairment.
- Infantile (type I): Symptoms typically appear before age 2, including seizures, enlarged brain and head, stiffness in limbs, and developmental delays.
- Juvenile (type II): Symptoms usually start after age 4, with speech problems, difficulty swallowing, poor coordination, and scoliosis.
- Adult: Symptoms can appear anytime in adulthood and are generally milder, with a wider variation in progression.
Most cases of Alexander disease are caused by a mutation in the GFAP gene. This gene provides instructions for making a protein called glial fibrillary acidic protein (GFAP), which is important for supporting the brain‘s white matter. The mutation in the GFAP gene causes this protein to accumulate, damaging the myelin and other brain cells.
There is no cure for Alexander disease, but treatment focuses on managing symptoms and improving quality of life. This may include medications for seizures, therapies to address developmental delays, and surgery to drain excess fluid from the brain.
