Charcot-Marie-Tooth Disease (CMT)

Types of CMT

Schwann cells form the myelin sheath in peripheral nerves by wrapping around them. Axons send chemical messages that attract Schwann cells and encourage myelin formation, and Schwann cells appear to send messages that nourish and protect axons. The genetic defects that cause Charcot-Marie-Tooth (CMT) often disrupt these interactions.

The many types of CMT are distinguished by age of onset, inheritance pattern, severity, and whether they are linked to defects in axon or myelin. The major categories of CMT are types 1 through 7 and the X-linked category, CMTX. Within each category, a specific disease associated with a particular gene is assigned a letter (e.g., CMT1A, CMT1B, etc.)

While these distinctions are useful, it is important to realize that because of the vast number of genetic defects that can lead to CMT, some people fall on the borders between different types, and many people have specific "subtypes" not detailed here.

Click on the links below to learn more about these subtypes of CMT:

• CMT1
• CMTX
• CMT4
• CMT2
• Severe, early onset CMT
• CMT 5, 6, and 7
• Intermediate CMT