CMT4G is caused by autosomal recessive mutations in the HK1 gene. CMT4G is also called Hereditary Motor and Sensory Neuropathy-Russe Type, or HMSN-R, for short. CMT4G is also called CMT-Russe.
CMT4G is found only within the Bulgarian and Spanish Romani populations. CMT4G symptom onset usually occurs in early childhood. CMTers who have CMT4G usually experience severe weakness in the lower legs by the time they are 10 years old and progressing to near total paralysis with age. CMTers who have CMT4G usually experience significant hand weakness by their mid-20’s with progressive worsening as they age.
Sensory nerve responses on nerve conduction study in CMTers who have CMT4G are absent and median motor conduction velocities are 33 meters/sec, and without prolonged distal latencies.
There is compelling evidence to suggest that CMT4G might be misclassified as a demyelinating CMT because CMT4G nerve conduction characteristics more closely resemble an axonal CMT (CMT2).