Alexander Disease Health Article

Definition

Alexander disease (ALX) is a rare and often fatal nervous system disorder that primarily occurs in infants and children.

Description

The main features of Alexander disease are progressive mental impairment and loss of motor control. Based on the age of onset and type of symptoms present, ALX has been classified into three forms: infantile, juvenile, and adult. Alexander disease is named for Dr. W. Stewart Alexander, an Australian pathologist who first described an infantile case in 1949. Since that time, 80% of cases described have also been the infantile form. About 14% of patients have the juvenile form, and adult cases are rare. All three forms of ALX are unified by the presence of Rosenthal fibers (RF), microscopic protein aggregates that are found in astrocytes in the brain and spinal cord. Though Rosenthal fibers are associated with other conditions, the numbers and distribution of RF-containing astrocytes are unique to Alexander disease. ALX is one of the leukodystrophies, a group of disorders characterized by imperfect formation or maintenance of white matter, the myelin sheath (insulation) that covers the nerves in the brain and spinal cord. Patients with ALX usually display loss of white matter, most prominently in the frontal lobes of the brain.

Demographics

Alexander disease is thought to be quite rare with approximately 200 cases described. Although there are no known prevalence estimates, the disease has been reported in both males and females and in various ethnic and racial groups.