Can Be Homozygous or Can Be Compound Heterozygous
CMT4C is caused by autosomal recessive mutations in the SH3TC2 gene. CMT4C tends to have significant variability amongst CMTers.
CMT4C symptom onset usually occurs by the time the CMTer is 10 years old. However, symptom onset can be as late as the CMTer’s 30’s. A CMTer who has CMT4C will usually experience the classic symptoms of CMT—lower and upper limb weakness, foot deformities, areflexia, loss of sensation, hand dexterity impairment, proprioception impairment, etc. The degree of severity to which the CMTer who has CMT4C will experience these symptoms is widely variable.
Some CMTers who have CMT4C become wheelchair dependent by their late teens, others by their mid-40’s, and others might not become wheelchair dependent. Disease progression of CMT4C is usually slow, but some can experience rapid progression.
Some CMTers who have CMT4C might experience cranial nerve involvement, including the vagus nerve, and a condition called neurogenic bladder and/or neurogenic bowel has been associated with CMT4C. Most CMTers who have CMT4C will also experience early onset scoliosis that can quickly become severe enough to require corrective surgery.