CMT4D is caused by autosomal recessive mutations in the NDRG1 gene. CMT4D was first reported to occur within the Romani community of Lom, Bulgaria. CMT4D was fist called Hereditary Motor and Sensory Neuropathy Lom, or HMSNL for short. There have since been reports of CMT4D outside of the Lom community, but these reports are still contained within the Romani population.
CMT4D symptom onset usually occurs by the time the CMTer is 10 years old, and most CMTers who have CMT4D become severely affected by the time they are in their 40’s. Most CMTers who have CMT4D become wheelchair dependent by their early 40’s, and most will lose hand function by the same age. Nerve conduction velocities in younger CMTers who have CMT4D are severely slowed, and then unattainable by the time the CMTer reaches 15 years old. All CMTers who have CMT4D become deaf by the time they are in their late 20’s, and most will experience scoliosis.