CMT4C
CMT4C is one of the more common recessive, demyelinating forms of CMT. It is caused by changes in the SH3TC2 gene, and a distinctive feature is an early curve of the spine (scoliosis) that often appears in childhood.
What CMT4C is
CMT4C is caused by changes in the SH3TC2 gene, which is important for the Schwann cells that build and maintain myelin, the insulation around nerves. When it does not work, the myelin does not form or hold up properly, producing a demyelinating neuropathy.
CMT4C usually begins in childhood, and one of its most recognizable features is an early curve of the spine (scoliosis), which is sometimes what leads to the diagnosis. Alongside this are the usual signs of CMT: weakness and sensory loss beginning in the feet and lower legs.
It is inherited recessively, meaning both copies of the gene are affected, and it is considered one of the more common of the recessive demyelinating CMTs. Some people also have hearing involvement.
How common it is. CMT4C is considered one of the more common of the recessive, demyelinating forms of CMT, though all recessive forms are far rarer than CMT1A.
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.
- Weakness and wasting of the feet and lower legs, usually beginning in childhood, with foot deformity and reduced reflexes
- Early-onset scoliosis (a curve of the spine), a characteristic feature
- Reduced sensation in the feet and lower legs
- Sometimes hearing involvement, from changes in the cranial nerves
- Markedly slowed nerve conduction on testing, reflecting the demyelinating process
Onset and how it changes over time
CMT4C usually begins in childhood, and the spinal curve can appear early and progress during the growing years, so it often needs its own monitoring alongside the neuropathy. The weakness is typically slowly progressive.
CMT4C is generally slowly progressive and not life-limiting, though the scoliosis can be significant and sometimes needs orthopedic care. Because the spine, and sometimes hearing, are involved, an experienced multidisciplinary team is especially useful.
How it is inherited
CMT4C is inherited in an autosomal recessive pattern: it takes two changed copies of the SH3TC2 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 and a 1 in 2 chance of being a carrier. A genetic counselor can explain what this means for siblings and family planning.
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 CMT4C?
CMT4C is one of the more common recessive, demyelinating forms of Charcot-Marie-Tooth disease. It is caused by changes in the SH3TC2 gene, which is important for the Schwann cells that build and maintain myelin, the insulation around nerves. When it does not work, the myelin does not form or hold up properly, producing a demyelinating neuropathy. To confirm which subtype you have, genetic testing is the way to know for certain.
What are the symptoms of CMT4C?
CMT4C usually begins in childhood with weakness and wasting of the feet and lower legs, foot deformity, and reduced reflexes, along with reduced sensation in the feet and lower legs. One of its most recognizable features is early-onset scoliosis, a curve of the spine, which is sometimes what leads to the diagnosis. Some people also have hearing involvement, and nerve conduction testing typically shows markedly slowed speeds, reflecting the demyelinating process.
What gene causes CMT4C?
CMT4C is caused by changes in the SH3TC2 gene. This gene is important for the Schwann cells that build and maintain myelin, the insulation around nerves, so when it does not work properly the result is a demyelinating neuropathy.
How is CMT4C inherited, and will my children get it?
CMT4C is inherited in an autosomal recessive pattern: it takes two changed copies of the SH3TC2 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 and a 1 in 2 chance of being a carrier. A genetic counselor can explain what this means for siblings and family planning.
Is CMT4C progressive?
CMT4C is generally slowly progressive and not life-limiting. The spinal curve can appear early and progress during the growing years, so it often needs its own monitoring alongside the neuropathy and sometimes needs orthopedic care. Because the spine, and sometimes hearing, are involved, an experienced multidisciplinary team is especially useful.
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 and OMIM 601596. Verified 2026-07-08.