GAN
Giant axonal neuropathy (GAN) is a rare, severe form that usually begins in early childhood and affects both the peripheral nerves and the brain. It is caused by loss of a protein called gigaxonin, and a distinctive clue is tightly curled hair unlike the parents.
What GAN is
GAN is caused by changes in the GAN gene, which makes a protein called gigaxonin. Gigaxonin helps the cell clear away and recycle part of its internal skeleton called neurofilaments. Without it, neurofilaments pile up and swell the nerve fibers into the giant axons that give the condition its name.
Unlike most forms of CMT, GAN affects both the peripheral nerves (causing the weakness and sensory loss familiar in CMT) and the central nervous system (the brain and spinal cord), which can add problems with balance, coordination, thinking, and sometimes seizures.
A well-known clue is the hair: many children with GAN have tightly curled or kinky hair that looks quite different from their parents. It is a severe, progressive condition that usually begins in early childhood.
How common it is. GAN is very rare, with a relatively small number of affected children described worldwide.
Common signs and symptoms
Reported symptoms and their severity vary from person to person, even within the same family. This is a general picture, not a prediction for any one person.
- Progressive weakness and sensory loss in the arms and legs, usually starting in early childhood
- Tightly curled or kinky hair, often unlike either parent
- Balance and coordination problems, from central nervous system involvement
- Difficulties with thinking and learning over time, and seizures in some children
- A progressive course that often affects walking during childhood
Onset and how it changes over time
GAN usually begins in early childhood, often before age five, and is progressive. Because it affects both the peripheral nerves and the brain, children commonly develop increasing weakness along with balance, coordination, and cognitive difficulties, and many become unable to walk during the second decade.
GAN is a serious, life-limiting condition, and care is centered on the whole child and family: supporting movement, breathing, learning, and comfort with an experienced team. Because research is active in this area, an accurate diagnosis and connection to specialists matter, and those conversations are best had with a team who knows your child.
How it is inherited
GAN is inherited in an autosomal recessive pattern: it takes two changed copies of the gene, one from each parent, who are usually unaffected carriers. When both parents carry a change, each child has about a 1 in 4 (25 percent) chance of being affected. A genetic counselor can explain testing for siblings and options for future pregnancies.
Autosomal recessive inheritance
It takes two changed copies, one from each parent, to cause CMT. When both parents are unaffected carriers, each child has about a 1 in 4 chance of being affected and a 1 in 2 chance of being a carrier.
- Affected
- Carrier
- Unaffected
- Male
- Female
This diagram shows a typical family. Real families vary, and it does not predict any specific outcome. A genetic counselor can walk through what it means for yours.
Frequently asked questions
What is giant axonal neuropathy (GAN)?
Giant axonal neuropathy (GAN) is a rare, severe form that usually begins in early childhood and affects both the peripheral nerves and the brain. It is caused by changes in the GAN gene, which makes a protein called gigaxonin. Gigaxonin helps the cell clear away and recycle neurofilaments, part of its internal skeleton, and without it neurofilaments pile up and swell the nerve fibers into the giant axons that give the condition its name. Genetic testing confirms the diagnosis.
What are the symptoms of GAN?
GAN causes progressive weakness and sensory loss in the arms and legs, usually starting in early childhood. Because it affects the central nervous system as well, children can also have balance and coordination problems, difficulties with thinking and learning over time, and seizures in some cases. A well-known clue is the hair: many children with GAN have tightly curled or kinky hair that looks quite different from their parents.
How is GAN inherited?
GAN is inherited in an autosomal recessive pattern: it takes two changed copies of the gene, one from each parent, who are usually unaffected carriers. When both parents carry a change, each child has about a 1 in 4 (25 percent) chance of being affected. A genetic counselor can explain testing for siblings and options for future pregnancies.
Is GAN progressive?
GAN usually begins in early childhood, often before age five, and is progressive. Because it affects both the peripheral nerves and the brain, children commonly develop increasing weakness along with balance, coordination, and cognitive difficulties, and many become unable to walk during the second decade. It is a serious, life-limiting condition, and care is centered on the whole child and family.
Why do children with GAN have curly hair?
A distinctive clue in GAN is the hair: many children have tightly curled or kinky hair that often looks quite different from either parent. It is one of the recognizable signs that can point toward the diagnosis, alongside the progressive weakness and sensory loss that usually begin in early childhood. An accurate diagnosis and connection to specialists matter, and those conversations are best had with a team who knows your child.
Confirm your subtype
If you have a clinical CMT diagnosis but no confirmed gene, genetic testing is how you learn your subtype. CMT Genie helps you and your provider get tested and connects you with telehealth genetic counseling.
Clinical information on this page is based on GeneReviews (Giant Axonal Neuropathy, NBK1136) and OMIM 256850. Verified 2026-07-08.