Giant Axonal Neuropathy
What is giant axonal neuropathy?
Giant axonal neuropathy occurs when axons, which are extensions of neurons, are abnormally large and do not function correctly. This condition affects both the central and peripheral nervous system.
This condition is extremely rare, with medical literature only describing 50 affected families.
What are the symptoms of giant axonal neuropathy?
This disorder is progressive, with symptoms beginning in childhood and worsening over time. They include:
- Trouble walking
- Loss of strength, sensation, and reflexes in the limbs
- Vision problems
- Hearing problems
At times the autonomic nervous system is affected, bringing symptoms like the loss of bladder control, constipation, reduction or loss in the ability to sweat, and heat intolerance.
As giant axonal neuropathy progresses, people may experience seizures, paralysis, and a decrease in mental function.
What causes giant axonal neuropathy?
A mutated GAN gene causes this condition, which results in a malfunction of the gigaxonin protein. It cannot adequately break down neurofilaments, which become packed in giant axons, causing issues that lead to the characteristic symptoms.
This mutated gene is inherited in an autosomal recessive pattern, meaning that both parents must pass down the mutation in order for a child to be affected.
How is giant axonal neuropathy diagnosed?
Doctors will conduct a physical exam followed by specialized tests, including a brain MRI, nerve conduction velocity, and a peripheral nerve biopsy. Genetic testing can be used to confirm a diagnosis.
What are the treatments for giant axonal neuropathy?
Treatment for this condition is symptomatic and usually requires a team of specialists. Genetic counseling is recommended for affected individuals and their families.