Charcot-Marie-Tooth disease (CMT) is an inheritable peripheral neuropathy. CMT is caused by any one of many different genetic mutations that can be passed onto one’s children. Peripheral neuropathy is any disease of the peripheral nervous system. Because CMT is caused by genetic mutations that disrupt peripheral nerves’ normal function, CMT is a peripheral neuropathy.
Autoimmune disease is any disease in which the body’s immune system attacks normal healthy cells and tissues as though they were foreign invaders. There are dozens of autoimmune diseases that affect many tissues, organs, and/or body systems. Some affect the peripheral nerves, such as Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Some affect the tissues of the joints, such as Rheumatoid Arthritis. Others, such as Multiple Sclerosis (MS), affect the central nervous system.
Many autoimmune diseases are also neuromuscular diseases. Neuromuscular refers to any disease that involves nerves and muscles to varying degrees. Many of these autoimmune diseases, such as CIDP and MS, are autoimmune neuromuscular disease and share many symptoms with CMT. CMT, too, is a neuromuscular disease.
Is CMT an Autoimmune Disease?
No, CMT is not an autoimmune disease. Although CMT shares many symptoms with autoimmune diseases such as MS, CMT is not a disease in which the body’s immune system is attacking peripheral nerve cells as though they are foreign invaders. Instead, CMT is a disease caused by any one of many different gene mutations that each disrupt the peripheral nerves’ normal function.
What is the Difference Between CMT and MS?
The major difference between CMT and MS is that CMT is a genetically caused disease of the peripheral nerves, but MS is caused by the body mistakenly attacking the central nervous system as though it was a foreign invader.
CMT is a disease of the peripheral nervous system. The peripheral nervous system is all the nerves, except the optic nerves, that connect everything in the body to the spinal cord and brain. CMT causes a disruption in the normal function of these nerves. As a consequence, muscles can become weakened, sensation can be reduced, etc.
The central nervous system is the brain, spinal cord, and optic nerves. In MS, the body’s immune system attacks the central nervous system and can cause many of the same symptoms as CMT, including muscle weakness and a loss of sensation. These two diseases, however, are very different from one another.
While some CMT subtypes can involve the central nervous system, such as CMTX1, for example, the reasons why are due to the genetic mutation responsible for the individual’s CMT. In contrast, MS fully spares the peripheral nervous system.
What is the Difference Between Peripheral Nerve Myelin and Central Nerve Myelin?
CMT primarily affects the peripheral nervous system, and in many subtypes the myelin sheath that surrounds and protects the peripheral nerves. On the other hand, MS primarily affects the central nervous system. Specifically, MS affects the myelin covering of the nerves in the brain and spinal cord. This means that MS, too, is demyelinating. However, MS affects only the myelin of the central nervous system and has no affect on the myelin of the peripheral nerves, and this is because of the type of cells that MS targets.
When CMT is demyelinating, it’s caused by CMT disrupting the normal function of peripheral nerve myelin. Peripheral nerve myelin is made by specialized cells found only in peripheral nerves, called Schwann cells. MS, however, targets the specialized cells that make central nerve myelin. These cells, called oligodendrocytes, are found only in the central nervous system and not in peripheral nerves.
Can Somebody who Has CMT also Have MS?
Yes, it is possible for somebody who has CMT to also develop MS or any other autoimmune disease. CMT does not prevent anybody from having any condition that the general public can have. Some research suggests neuromuscular diseases such as CMT might increase the risk for developing MS, but the CMT experts do not believe this to be true in CMT.
Can MS Treatments Work for CMT?
No, treatments for MS do not work for CMT. Many treatments for MS focus on suppressing the immune system. This doesn’t work in CMT because CMT is not caused by the body’s immune system mistakenly attacking normal cells. Other treatments for MS focus on regenerating the myelin damaged by MS. These treatments do not work in CMT because these treatments target the central nervous system myelin-producing cells called oligodendrocytes. These specialized cells are not present in peripheral nerves. Therefore, these treatments have no clinical benefit in CMT.
CMT and many other neuromuscular diseases, including autoimmune diseases, share many symptoms. While CMT is a neuromuscular disease, it is different than autoimmune neuromuscular diseases, such as MS. Both CMT and MS can cause demyelination, and with it, share many symptoms, but this is where the similarities end.
The demyelination that MS causes is different than what CMT can cause, and it is specific only to the central nervous system. Also, MS is a disease caused by the body’s immune system attacking normal cells and tissue, but CMT on the other hand, is caused by any one of many different genetic mutations that each disrupt the peripheral nerves’ normal function.
Published: July 16, 2023