Canavan Disease
Canavan disease is an inherited disorder of aspartic acid metabolism (breakdown and use). It is characterized by degeneration (falling apart) of the white matter of the brain.
Causes, incidence, and risk factors
Canavan disease is inherited as an autosomal recessive trait. It is more common among Ashkenazi Jews than in the general population. A deficient enzyme, aspartoacylase, results in the accumulation of material called N-acetylaspartic acid in the brain. This causes the white matter of the brain to deteriorate. Typically, symptoms begin in the first year of life. Parents tend to notice when a child is not reaching particular developmental milestones, including lack of head control. The child will also have poor muscle tone. Eventually, the child can develop feeding problems, seizures, and loss of vision. Although death often occurs before 18 months of age, some patients live until they are teenagers or, rarely, young adults.
Symptoms
- A family history of Canavan disease.
- Decreased muscle tone (hypotonia), especially of the neck muscles.
- Abnormal posture with flexed arms and straight legs.
- Feeding difficulties.
- Nasal regurgitation (backflow of food material into the nose).
- Swallowing difficulties.
- Reflux with vomiting.
- Increasing head size (macrocephaly).
- Head lag (lack of head control when baby is pulled from lying to sitting position).
- Failure to meet milestones.
- Seizures.
- Severe mental retardation.
- Blindness.
Treatment aims to ease the symptoms of the disease. There is no specific treatment.
Prevention
Genetic counseling is recommended for prospective parents with a family history of Canavan disease, and should be considered if both parents are of Ashkenazi Jewish descent. For this group, DNA testing can almost always tell if one or both parents is a carrier.
Credit: National Institute of Health.