Can Be Homozygous or Can Be Compound Heterozygous
CMT4K is caused by autosomal recessive mutations in the SURF1 gene. CMT4K tends to be a fairly severe type of CMT.
CMT4K symptom onset usually occurs in early childhood. CMTers who have CMT4K will usually experience severe weakness in the lower legs and lower arms along with significant sensory loss and absent reflexes by the time they are 10 years old. CMTers who have CMT4K will usually develop kyphoscoliosis early on; and they might also experience nystagmus, late-onset cerebellar ataxia, isolated mitochondrial complex IV deficiency, and lactic acidosis when resting.