This rare genetic disorder may affect fewer than 100 people worldwide. You may experience difficulty walking or numbness in your arms and legs at first, but it can develop into more serious symptoms.

Giant axonal neuropathy (GAN) is a very rare, inherited disorder. It affects your nerve cells. After a while, it affects your entire nervous system.

You may experience difficulty walking or numbness in your arms and legs at first, but it can progress into more severe symptoms that include difficulty breathing, seizures, or paralysis.

People usually begin to have symptoms by 5 years old. Some people with a milder form may begin to have symptoms at later ages.

Here’s what to know about GAN, including symptoms to look for and possible outcomes.

GAN is a genetic disorder. It causes a mutation in the GAN1 gene. The mutation changes how your nerves function. In turn, that changes how they communicate with your brain and spinal cord, which comprise your central nervous system.

GAN also causes the nerves in your peripheral nervous system to malfunction. The peripheral nervous system is the nerve network that branches out from your brain and spinal column.

GAN is an age-related, progressive, and neurodegenerative disease. That means it gets worse over time. It usually starts in very young children.

The malfunction in your GAN1 gene causes a problem with the natural turnover of filaments located within your axons, which are part of your nerve cells. The axons are the messengers of your nerve cells. They communicate with your central nervous system.

Usually, your body breaks down and replaces the filaments in the axons. But in GAN, your body doesn’t break them down. They collect in the axon, enlarging it. The enlarged axon causes the nerve to stop working or communicating. The nerves may eventually die.

This causes problems moving or feeling because your nerve cells can’t talk with each other.

GAN gets its name from the larger-than-usual size of the nerve axons.

GAN usually appears very early in infants or children younger than 5 years. Often, a child with GAN will have very tightly curled, kinky, and pale hair unlike other family members’ hair. The difference in hair may be due to a buildup of excess keratin.

GAN symptoms tend to progress with age.

Early symptoms include:

  • clumsiness
  • weakness
  • problems walking
  • numbness in arms and legs
  • slowed mental development

More severe symptoms that can develop later include:

  • loss of coordination
  • seizures
  • loss of body control
  • fast back-and-forth movement of the eyes
  • paralysis
  • difficulty breathing or swallowing

Most children need to use a wheelchair sometime between 10 and 20 years old.

What other health conditions can giant axonal neuropathy lead to?

GAN can lead to other related conditions, including:

  • scoliosis
  • hearing and vision loss
  • visual and hearing problems

People with GAN inherit it from their parents, who each have a copy of the gene that causes the disorder.

Parents usually don’t have any symptoms. Because it’s recessive, you need two copies of the gene to develop GAN.

In GAN, a gene mutation causes you to have much less of a certain substance in your cells. This substance naturally breaks down protein filaments in your nerves so that the nerves can function correctly.

When the filaments aren’t broken down and replaced, they enlarge the nerve axon. The nerve then stops working.

Both GAN and amyotrophic lateral sclerosis (ALS) are neurodegenerative. That means they affect your nervous system and tend to worsen over time.

Both conditions cause nerve death that leads to muscle weakness, loss of bodily control or function, and problems swallowing or breathing.

But they are different in many ways, from their genetic origins to the age of onset.

Here is a quick comparison of ALS and GAN:

Onsetusually ages 55–75usually starts by age 5
Outlookmost live 3–5 years after diagnosislive to their 20s
Riskmostly with no family historygenetic link

Right now, GAN doesn’t have a cure.

But your healthcare team can help you manage your symptoms. Each person has different symptoms. Your team can help you identify and treat them.

A healthcare team’s main goals are supporting physical and intellectual development and a good quality of life.

Your team of professionals may include:

  • neurologists
  • orthopedic surgeons
  • physical and occupational therapists
  • psychologists
  • speech and language pathologists

GAN is quite rare. Experts have published research on fewer than 50 cases. Of those, most people lived to be in their 20s.

Some people with a milder form and straight hair develop symptoms later. The symptoms may progress slowly. People with a milder type may have symptoms similar to Charcot-Marie-Tooth disease, as well as less curly hair rather than straight.

Researchers began conducting the first gene therapy study with humans in 2015.

As of 2023, researchers are still conducting clinical trials of gene replacement therapy for people ages 3 and older. The study is ongoing.

Researchers are trying to determine whether treatment with various medications is safe and helpful.

You may find these resources helpful:

  • Hannah’s Hope Fund is a nonprofit that raises funds for clinical research. It also seeks to raise awareness about GAN and provide support for families. The nonprofit’s website has lots of information and resources for families and caregivers.
  • The National Institute of Neurological Disorders and Stroke offers patient resources, including a list of patient groups. As of November 2023, the institute didn’t have organizations listed specifically for GAN. However, it did have patient organization listings for different types of neuropathy, including peripheral neuropathy.

Giant axonal neuropathy (GAN) is a progressive neurodegenerative disorder. It develops from a genetic mutation that causes your nerve cells to stop functioning. Doctors usually diagnose it in children ages 5 years or younger.

Symptoms may start with clumsiness but may progress to loss of control over bodily functions, like walking and thinking.

GAN doesn’t have a current cure, but researchers are developing new therapies with promise in treating GAN. In the meantime, your healthcare team can help you or your loved one reach developmental milestones and have a better quality of life.