A Look at the Differences Between CMT Type 1 and CMT Type 2

A Look at the Differences Between CMT Type 1 and CMT Type 2

Charcot-Marie-Tooth Disease (CMT) is a kind of inherited peripheral neuropathy that affects a large population in the United States. The two most popular kinds of Charcot-Marie-Tooth are CMT type 2 (axonal) and CMT type 1 (demyelinating). Statistics show that approximately 19 out of 100,000 people suffer from such a condition. The CMT usually affects peripheral nerves, which transmit signal data to the spinal cord and brain, causing more relay sensations like touch and pain. This painful condition is transmitted across the body, reducing body sensations amicably. 

Charcot-Marie-Tooth Disease Type 1

CMT 1 is the popular CMT that affects many residents across the United States. This disease is inherited within the autosomal dominant pattern.

The Symptoms of the CMT 1

This disease is characterized by atrophy and muscle weakness, which trigger sensations and frequent ankle pains. It usually begins in childhood and then continues to adulthood with severe impacts on the body. CMT 1 affects body parts like the forearms, feet, lower legs, and hands. In addition, people suffering from such diseases encounter breathing difficulties, especially while sleeping.

The Causes of the CMT 1

It’s caused by damage to the myelin sheath covering nerves. CMT 1 is also caused by the mutation around the PMP22 gene or duplication, making it the most popular kind of CMT. However, PMP22 duplication results in the peripheral myelin accumulation of protein 22. PMP22 is the best element precisely for maintaining and building the myelin sheath.

The Effects of the CMT 1

Individuals with CMT 1 experience pain around their distal muscles and gradual progressive weakness. Its severe painful condition starts at the ankles and feet that appear as foot drops. It also affects the lower parts of the forearms and legs and controls the entire foot.

Charcot-Marie-Tooth Disease Type 2

CMT 2 is more familiar to CMT 1 but less popular. It’s inherited around the autosomal dominant pattern but can also be inherited from the autosomal recessive pattern. It accounts for between 12% and 36% of the majority of the CMT cases.

The Symptoms of the CMT 2

It’s characterized by the variable foot deformity, distal weakness, sensory loss, decreased deep tendon reflexes, and atrophy. Its onset symptoms start appearing between 5-25 years. It’s less severe than the CMT 1 but with many motors regarding sensory involvement.

The Causes of CMT 2

Unlike CMT 1, which is caused by the damage towards the myelin insulating axons, CMT 2 is caused by the damage of the axon’s nerves directly. Therefore, it’s popularly known as the axonal CMT. Research shows that CMT2A is the most popular kind of CMT 2 caused by the damages within the MFN2 gene. This CMT 2 subtype is approximately 20 percent of all axonal CMT cases. The MFN2 gene is represented as the mitofusin 2. This protein usually engages in cellular mitochondria fusion. Other CMT 2 include CMT2T, CMT2B, CMT2K, CMT2D, and much more.

The Effects of the CMT 2

People with CMT 2 mostly develop contractures which eventually lead to foot and hand deformities. It usually occurs due to the weakness around the joints, increasing pulling and contracting on the joints. Eventually, bones within the joint will move to an abnormal area.