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Infantile Neuroaxonal Dystrophy

Neurological disease worsens over time

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Updated October 04, 2006

Infantile neuroaxonal dystrophy (old name: Seitelberger disease) is an inherited disorder that affects the nerves in the brain and other parts of the body, causing them to stop working over time. The symptoms of the disorder come from the abnormal build-up of toxic substances (sometimes called spheroid bodies) in the nerves that prevents them from working properly. It is not known how or why this happens. In 2006 researchers identified a gene called PLA2G6 on chromosome 22 as being associated with infantile neuroaxonal dystrophy, and scientists are studying what role this gene plays in causing the disorder.

Infantile neuroaxonal dystrophy affects both males and females, but it is not known how often it occurs in people in the world.

Symptoms
The symptoms of infantile neuroaxonal dystrophy start slowly and get progressively worse over time. Symptoms usually begin between 6 months and 3 years of age, and include:

  • Slowing of growth and development—the child starts to fall behind other children his/her age. Over time, the child loses the ability to do things he/she could already do (such as sit up, crawl, or stand). The muscles become weak and floppy (hypotonic).
  • Slowing of the child’s mental and language development—the child starts to fall behind other children his/her age. Over time, the child loses the ability to do things he/she could already do, including saying words and communicating. Eventually the child will no longer be responsive or aware of his/her surroundings.
  • Eye changes such as rapid eye twitching (nystagmus) and vision getting worse over time. The child will eventually become blind.

Diagnosis
Diagnosis of infantile neuroaxonal dystrophy is based on the symptoms the child is having, the symptoms starting before age 3 years, and examination of a sample (biopsy) of skin, nerve, or tissue around the eye (conjunctiva). In infantile neuroaxonal dystrophy, the sample will show the presence of the deposits (spheroid bodies) in the nerves.

Because infantile neuroaxonal dystrophy is rare, it may be difficult to diagnose correctly. Similar symptoms may occur in gangliosidosis, Leigh’s disease, and NBIA (Hallervorden-Spatz disease). The muscle weakness and loss of voluntary movement can also be found in myopathy and spinal muscular atrophy.

Treatment
There is presently no specific treatment that can stop or reverse the symptoms of infantile neuroaxonal dystrophy. Therefore, treatment focuses on the symptoms that each individual has. Physical and occupational therapy can help maintain function and motion of joints and prevent or reduce the development of muscle contractures. When eating and swallowing become difficult due to muscle weakness, a feeding tube can provide nutrition.

Over time the combination of the diseased brain and physical weakness becomes too great. Weak chest muscles make it hard to breathe, so pneumonia may occur frequently and recovery from it may be difficult. Children with infantile neuroaxonal dystrophy do not usually live beyond 5-10 years of age.

Future research
Discovery of the PLA2G6 gene means that a medical test can be developed to help families determine their chances of passing infantile neuroaxonal dystrophy on to their children. The child must inherit two copies of the defective gene, one from each parent, in order to have the disorder.

Research will be needed to determine how the PLA2G6 gene is involved in the development of infantile neuroaxonal dystrophy. Once this is understood, this could possibly lead to the development of medications to treat the disorder. Research of PLA2G6 could also lead to better understanding of other neurological disorders such as Parkinson’s disease.

Sources:
- National Health Service UK. Infantile Neuroaxonal Dystrophy Factsheet
- National Organization for Neurological Disorders and Stroke. NINDS Infantile Neuroaxonal Dystrophy Information Page
- Nardocci, Nardo. “Infantile neuroaxonal dystrophy.” Orphanet Encyclopedia (2004). Accessed at http://www.orpha.net/data/patho/GB/uk-INAD.pdf
- Morgan, Neil, et al. “PLA2G6, encoding a phospholipase A2, is mutated in neurodegenerative disorders with high brain iron.” Nature Genetics (2006) 38:752-754.

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