Canavan disease

  • Definition
    • Canavan disease is a condition that affects how the body breaks down and uses aspartic acid.

  • Alternative Names
    • Spongy degeneration of the brain; Aspartoacylase deficiency

  • Causes
    • Canavan disease is passed down (inherited) through families. It is more common among the Ashkenazi Jewish population than in the general population.

      The lack of the enzyme aspartoacylase leads to a buildup of material called N-acetylaspartic acid in the brain. This causes the white matter of the brain to break down.

  • Symptoms
    • Symptoms often begin in the first year of life. Parents tend to notice it when their child is not reaching certain developmental milestones, including head control.

      Symptoms include:

      • Abnormal posture with flexed arms and straight legs
      • Food material flows back into the nose
      • Feeding problems
      • Increasing head size
      • Irritability
      • Poor muscle tone, especially of the neck muscles
      • A lack of head control when baby is pulled from a lying to a sitting position
      • Poor visual tracking, or blindness
      • Reflux with vomiting
      • Seizures
      • Severe intellectual disability
      • Swallowing difficulties
  • Exams and Tests
    • A physical exam may show:

      • Exaggerated reflexes
      • Joint stiffness
      • Loss of tissue in the optic nerve of the eye

      Tests for this condition include:

      • Blood chemistry
      • CSF chemistry
      • Genetic testing for aspartoacylase gene mutations
      • Head CT scan
      • Head MRI scan
      • Urine chemistry for elevated aspartic acid
  • Treatment
    • Treatment mostly aims to ease the symptoms of the disease. Lithium and other drugs are being studied.

  • Support Groups
  • Outlook (Prognosis)
    • With Canavan disease, the central nervous system breaks down. People are likely to become disabled.

      Death often occurs before 18 months of age. However, some people live until they are teenagers or, rarely, young adults.

  • Possible Complications
    • This is often a fatal disorder. It includes severe disabilities such as:

      • Blindness
      • Inability to walk
      • Intellectual disability
  • 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 people who want to have children and have a family history of Canavan disease. Counseling should be considered if both parents are of Ashkenazi Jewish descent. For this group, DNA testing can almost always tell if the parents are carriers.

      A diagnosis may be made before the baby is born (prenatal diagnosis) by testing the amniotic fluid, the fluid that surrounds the womb.

  • References
    • Matalon KM, Matalon RK. Aspartic acid (Canavan disease). In: Kliegman RM, Stanton BF, St Geme JW III, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 85.