Charcot-Marie-Tooth Disease (CMT)
What is Charcot-Marie-Tooth disease type 2 (CMT2)?
CMT Type 2 (CMT2) is a subtype of CMT that is similar to CMT1 but is less common. CMT2 is typically autosomal dominant, but in some cases can be recessive.
What are the symptoms of CMT2?
CMT2 is characterized by muscle weakness and atrophy, and changes in sensation, mostly in the periphery of the body — particularly in the feet, lower legs, hands and forearms. CMT2 symptoms are similar to those of CMT1, but there is more variability in age of onset and degree of disability.
CMT2 also is sometimes associated with a treatable condition called restless leg syndrome, an irresistible urge to move the legs while sitting or lying down. For more, see Signs and Symptoms.
What causes Charcot-Marie-Tooth disease type 2 (CMT2)?
CMT2 is caused by direct damage to the nerve axon itself in comparison to CMT1 which results from damage to the myelin sheath insulating the axon. CMT2 is commonly referred to as “axonal” CMT.
CMT2A is the most common subtype of CMT2 and is caused by defects in the MFN2 gene. The MFN2 gene encodes for Mitofusin 2, which is a protein involved in the fusion of cellular mitochondria.
Other more rare forms of CMT2 and their gene defects include:
CMT2B is caused by defects in the RAB7 gene.
CMT2C is caused by defects in the TRPV4 gene.
CMT2D is caused by defects in the GARS gene.
CMT2E is caused by defects in the NEFL gene.