SURF1-related Charcot-Marie-Tooth disease type 4 (CMT4K) is a type of nerve disorder that usually begins in childhood. It is marked by a severe, progressive loss of nerve function that affects movement and sensation in the hands and feet. The condition is known for its demyelinating sensorimotor neuropathy, meaning that the protective covering of nerves is damaged, leading to difficulties with muscle control and sensory perception. People with this condition often experience significant muscle weakness and atrophy in their extremities. Other features may include problems with balance and coordination, reflected by symptoms such as nystagmus and cerebellar ataxia. Some individuals may also develop skeletal issues like kyphoscoliosis or show changes in brain imaging studies, such as lesions in certain brain areas.

Common signs and symptoms in people with SURF1-related CMT4K include severe, progressive weakness and wasting of muscles in the hands and feet, and reduced sensation in the lower limbs, particularly for vibrations and pinprick sensations. Additional findings can include lactic acidosis, absent reflexes (areflexia), and markedly slow motor nerve conduction velocities. Some individuals also have symptoms such as kyphoscoliosis, nystagmus, hearing loss, and cerebellar ataxia, along with abnormalities seen on brain MRI.

This condition is caused by mutations in the SURF1 gene. Changes in this gene lead to problems with the normal functioning of nerves, which causes the demyelinating neuropathy seen in this disease. The genetic nature of this disorder means that it is inherited, typically in an autosomal recessive pattern. Associated genes include SURF1.