What Is Canavan Disease?
Canavan disease is an inherited condition that destroys the myelin sheath, the white matter that insulates nerve cells in the brain. This impairs the ability of nerve cells to communicate with other cells. Canavan disease is caused by mutations in the ASPA gene that result in a deficiency of an enzyme called aspartoacylase. This enzyme breaks down a material called N-acetyl-L-aspartic acid (NAA) in the brain. Without enough enzyme, the NAA builds up in the brain and destroys its white matter.
Neonatal/infantile Canavan disease is the most common form of Canavan disease. Affected children develop muscle weakness and developmental delay, leading to severe mental disability. Developmental delays typically begin at three to five months of age with poor muscle tone (hypotonia) which causes problems with an infant's ability to turn over, control head movements, and to sit up. The infant's head also becomes rapidly larger (macrocephaly). Over time, children with the condition may become unable to swallow and may develop sleep disturbances, seizures, and blindness.
Individuals with the mild/juvenile form of Canavan disease may have mild speech or motor delays beginning in childhood. However, for some affected individuals, the delays may be so mild that they go unrecognized or so non-specific that affected individuals may be undiagnosed.
How Common Is Canavan Disease?
The prevalence of Canavan disease in the general population is unknown. Among people of Ashkenazi Jewish descent, the prevalence is 1 in 6,400 to 1 in 13,500 individuals.
How Is Canavan Disease Treated?
At this time, there is no cure for Canavan disease. Treatment for the neonatal/infantile form of the disease focuses on keeping the affected person comfortable with proper nutrition and hydration and controlling seizures with medication. Physical therapy can be beneficial to maximize ability and to minimize contractures. Individuals with the mild/juvenile form of Canavan disease may need speech therapy or tutoring but generally, do not require special medical care.
What Is the Prognosis for a Person with Canavan Disease?
Most people with the neonatal/infantile form of Canavan disease die in childhood, although some survive into their teens or early twenties and beyond, depending on the medical care provided. Individuals with the mild/juvenile form of the disease do not typically have a shortened lifespan.