What Is Giant Axonal Neuropathy? | HealthInfi

Giant Axonal Neuropathy

Giant axonal neuropathy is a rare, autosomal recessive neurological disorder that causes disorganization of neurofilaments. Neurofilaments form a structural framework that helps to define the shape and size of neurons and are essential for normal nerve function.

Giant axonal neuropathy (GAN) is a rare inherited genetic disorder that affects both the central and peripheral nervous systems.  The majority of children with GAN will begin to show symptoms of the disease sometime before five years of age.  Signs of GAN usually begin in the peripheral nervous system, which controls movement and sensation in the arms, legs, and other parts of the body.

Giant axonal neuropathy is an inherited condition characterized by abnormally large and dysfunctional axons called giant axons. Axons are specialized extensions of nerve cells (neurons) that transmit nerve impulses. Symptoms of the disorder first become apparent in the peripheral nervous system, in which long axons connect the brain and spinal cord (central nervous system) to muscles and to sensory cells that detect sensations such as touch, pain, heat, and sound. However, axons in the central nervous system are affected as well.

The typical symptoms of GAN are clumsiness and muscle weakness that progresses from a “waddling gait” to a pronounced difficulty in walking.  Additional symptoms include numbness or lack of feeling in the arms and legs, seizures, nystagmus (rapid back and forth movement of the eyes), and impaired cognitive development.  A characteristic sign of the disease is dull, tightly curled hair that is markedly different from the parents’ in color and texture.

Researchers have discovered more than 20 different mutations associated with GAN in a gene, GAN1, which makes a protein called gigaxonin.   These mutations disrupt the regulation or production of gigaxonin in the nervous system.  As a result, axons, which are the long tails of neurons that allow them to communicate with other nerve cells, swell up with tangled filaments and become abnormally large.  Eventually these axons deteriorate and cause problems with movement and sensation since neurons are no longer able to communicate with each other.

Doctors diagnose GAN by using several tests, including one that measures nerve conduction velocity, a brain MRI, and a peripheral nerve biopsy (in which a bit of tissue from a peripheral nerve is removed and examined to look for swollen axons).  A definitive diagnosis using genetic testing is available on a research basis only.

GAN is inherited in an autosomal recessive pattern, which means that both parents of a child with GAN have to carry a copy of the mutated gene.   Parents, typically, will show no signs of the disease.

The signs and symptoms of giant axonal neuropathy generally begin in early childhood and get worse over time. Most affected individuals first have problems with walking. Later they may lose sensation, strength, and reflexes in their limbs; experience difficulty coordinating movements (ataxia); and require wheelchair assistance. Visual and hearing problems may also occur. Many individuals with this condition have extremely kinky hair as compared to others in their family.

It is possible that the main title of the report Giant Axonal Neuropathy is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Giant axonal neuropathy can also impact the autonomic nervous system, which controls involuntary body processes. Affected individuals may experience problems with the release of urine (neurogenic bladder), constipation, heat intolerance, and reduction in or loss of the ability to sweat Read More