What Is CMT-ATP6?
CMT-ATP6 is a type of CMT caused by mutations in the MT-ATP6 gene. This gene lives in mitochondrial DNA rather than regular coding DNA, and provides instructions for making a component of the enzyme that generates cellular energy within mitochondria. Mutations in the MT-ATP6 gene disrupt this function, leading to impaired nerve signal transmission.
CMT-ATP6 follows a mitochondrial inheritance pattern, meaning the causative mutation is carried in the mitochondrial DNA and passed from a mother to her children.
Clinical Features
The age of symptom onset in CMT-ATP6 is variable, ranging from childhood to adulthood. Symptoms typically begin in the lower extremities and progress over time to involve the upper limbs. Nerve conduction studies usually show somewhat slowed conduction velocities and reduced amplitudes, consistent with an axonal form of CMT.
CMT-ATP6 symptoms may include:
- Weakness in the feet and lower legs
- Muscle atrophy
- Foot drop
- Reduced or absent reflexes
- Reduced sensation
- A steppage-style walking pattern
- Foot deformities, including high arches, and hammertoes (clawed toes)
- Progressive involvement of the hands and forearms
- Difficulty with fine motor skills and manual dexterity
- Additional symptoms not listed here
Disease Course
CMT-ATP6 shows wide variability in severity and progression. Some individuals are mildly affected, while others develop a more severe disease. Disease progression is generally slow, and life expectancy is not reduced.
