Aspartoacylase deficiency

Definition

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.

Alternative Names

Causes

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

Exams and Tests

• Hyperreflexia (reflexes are exaggerated)
• Joint stiffness
• Optic atrophy (wasting away)

• Head CT showing degeneration of white matter (leukodystrophy)
• Head MRI scan showing degeneration of white matter (leukodystrophy)
• Urine chemistry, increased N-acetylaspartic acid
• CSF chemistry, increased N-acetylaspartic acid
• Blood chemistry, increased N-acetylaspartic acid
• Genetic testing for aspartoacylase gene mutations

Treatment

Treatment aims to ease the symptoms of the disease. There is no specific treatment.

Support Groups

Additional information and resources are available from:

Canavan Foundation

www.canavanfoundation.org

877-4-CANAVAN

Outlook (Prognosis)

With Canavan disease, the central nervous system degenerates, and progressive disability is likely. Death usually occurs in the first 1 to 2 decades of life.

Possible Complications

This is often a fatal disorder and includes severe disabilities such as mental retardation, blindness, and inability to walk.

When to Contact a Medical Professional

Call your health care provider if your child has any symptoms of Canavan disease.

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.