What Is CMT-CTDP1?
CMT-CTDP1 is a type of CMT caused by autosomal recessive mutations in the CTDP1 gene. This gene provides instructions for making a protein phosphatase that regulates RNA polymerase II during gene transcription, a process fundamental to normal cell development throughout the body. Mutations in the CTDP1 gene disrupt this regulatory function, affecting the development and maintenance of the eyes, facial structures, and peripheral nerves.
CMT-CTDP1 is autosomal recessive, meaning that both copies of the gene must have a mutation to cause this subtype.
Clinical Features
The age of symptom onset in CMT-CTDP1 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 slowed conduction velocities, consistent with a demyelinating form of CMT.
CMT-CTDP1 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-CTDP1 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.
